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Impaired T cell immunity with aging increases mortality from infectious disease. The branching of Asparagine-linked glycans is a critical negative regulator of T cell immunity. Here we show that branching increases with age in females more than males, in naïve more than memory T cells, and in CD4(+) more than CD8(+) T cells. Female sex hormones and thymic output of naïve T cells (T(N)) decrease with age, however neither thymectomy nor ovariectomy altered branching. Interleukin-7 (IL-7) signaling was increased in old female more than male mouse T(N) cells, and triggered increased branching. N-acetylglucosamine, a rate-limiting metabolite for branching, increased with age in humans and synergized with IL-7 to raise branching. Reversing elevated branching rejuvenated T cell function and reduced severity of Salmonella infection in old female mice. These data suggest sex-dimorphic antagonistic pleiotropy, where IL-7 initially benefits immunity through T(N) maintenance but inhibits T(N) function by raising branching synergistically with age-dependent increases in N-acetylglucosamine.

© Zocchi et al. Osteosarcoma is the most common primary malignant neoplasm of bone and typically occurs in children and young adults. As a highly metastatic malignancy, 15- 20% of osteosarcoma patients are diagnosed after the tumor has already metastasized (typically to the lungs), which translates to 5-year survival rates of < 40%. Here, we tested the effect of the cyclin-dependent kinase (CDK) inhibitor flavopiridol (alvocidib) in U2OS, SaOS-2, SJSA-1, and 143B osteosarcoma tumor cells in vitro and in vivo. Our results show that flavopiridol can drastically decrease survival in these osteosarcoma cell lines at nanomolar concentrations and induce mitotic catastrophe in p53-null osteosarcomas. We also performed transcriptome analysis (RNA-seq) of flavopiridoltreated osteosarcoma cells, which revealed significant changes in genes coding for proteins involved in cell-cell and cell-matrix adhesions, including cadherin 3 (CDH3) and 4 (CDH4). These transcriptional changes translated to a striking reduction in the ability of osteosarcoma cells to migrate and invade in vitro. Further, in vivo assessment of the effects of flavopiridol on osteosarcoma metastasis resulted in a significant reduction in the number of lung metastases in mice treated with flavopiridol at concentrations that are physiologically tolerable. This study suggests that flavopiridol, likely in combination with other cytotoxic chemotherapeutic agents, may be a promising drug for the treatment of osteosarcoma.

Enhancing neurogenesis may be a powerful stroke therapy. Here, we tested in a rat model of ischemic stroke the beneficial effects of NSI‐189, an orally active, new molecular entity (mol. wt. 366) with enhanced neurogenic activity, and indicated as an anti‐depressant drug in a clinical trial (Fava et al., 2015, Molecular Psychiatry, DOI: 10.1038/mp.2015.178) and being tested in a Phase 2 efficacy trial (ClinicalTrials.gov, 2016, ClinicalTrials.gov Identifier: NCT02695472) for treatment of major depression. Oral administration of NSI‐189 in adult Sprague–Dawley rats starting at 6 hr after middle cerebral artery occlusion, and daily thereafter over the next 12 weeks resulted in significant amelioration of stroke‐induced motor and neurological deficits, which was maintained up to 24 weeks post‐stroke. Histopathological assessment of stroke brains from NSI‐189‐treated animals revealed significant increments in neurite outgrowth as evidenced by MAP2 immunoreactivity that was prominently detected in the hippocampus and partially in the cortex. These results suggest NSI‐189 actively stimulated remodeling of the stroke brain. Parallel in vitro studies further probed this remodeling process and demonstrated that oxygen glucose deprivation and reperfusion (OGD/R) initiated typical cell death processes, which were reversed by NSI‐189 treatment characterized by significant attenuation of OGD/R‐mediated hippocampal cell death and increased Ki67 and MAP2 expression, coupled with upregulation of neurogenic factors such as BDNF and SCF. These findings support the use of oral NSI‐189 as a therapeutic agent well beyond the initial 6‐hr time window to accelerate and enhance the overall functional improvement in the initial 6 months post stroke.

Class-switch DNA recombination (CSR) and somatic hypermutation (SHM), which require activation-induced cytidine deaminase (AID), and plasma cell differentiation, which requires B lymphocyte–induced maturation protein-1 (Blimp-1), are critical for the generation of class-switched and hypermutated (mature) Ab and autoantibody responses. We show that histone deacetylase inhibitors valproic acid and butyrate dampened AICDA/Aicda (AID) and PRDM1/Prdm1 (Blimp-1) mRNAs by upregulating miR-155, miR-181b, and miR-361 to silence AICDA/Aicda, and miR-23b, miR-30a, and miR-125b to silence PRDM1/Prdm1, in human and mouse B cells. This led to downregulation of AID, Blimp-1, and X-box binding protein 1, thereby inhibiting CSR, SHM, and plasma cell differentiation without altering B cell viability or proliferation. The selectivity of histone deacetylase inhibitor–mediated silencing of AICDA/Aicda and PRDM1/Prdm1 was emphasized by unchanged expression of HoxC4 and Irf4 (important inducers/modulators of AICDA/Aicda), Rev1 and Ung (central elements for CSR/SHM), and Bcl6, Bach2, or Pax5 (repressors of PRDM1/Prdm1 expression), as well as unchanged expression of miR-19a/b, miR-20a, and miR-25, which are not known to regulate AICDA/Aicda or PRDM1/Prdm1. Through these B cell–intrinsic epigenetic mechanisms, valproic acid blunted class-switched and hypermutated T-dependent and T-independent Ab responses in C57BL/6 mice. In addition, it decreased class-switched and hypermutated autoantibodies, ameliorated disease, and extended survival in lupus MRL/Faslpr/lpr mice. Our findings outline epigenetic mechanisms that modulate expression of an enzyme (AID) and transcription factors (Blimp-1 and X-box binding protein 1) that are critical to the B cell differentiation processes that underpin Ab and autoantibody responses. They also provide therapeutic proof-of-principle in autoantibody-mediated autoimmunity.

SummaryClass-switch DNA recombination (CSR) is central to the antibody response, in that it changes the immunoglobulin heavy chain (IgH) constant region, thereby diversifying biological effector functions of antibodies. The activation-induced cytidine deaminase (AID)-centered CSR machinery excises and rejoins DNA between an upstream (donor) and a downstream (acceptor) S region, which precede the respective constant region DNA. AID is stabilized on S regions by 14-3-3 adaptors. These adaptors display a high affinity for 5′-AGCT-3′ repeats, which recur in all S regions. However, how 14-3-3, AID, and the CSR machinery target exclusively the donor and acceptor S regions is poorly understood. Here, we show that histone methyltransferases and acetyltransferases are induced by CD40 or Toll-like receptor signaling and catalyze H3K4me3 and H3K9ac/K14ac histone modifications, which are enriched in S regions but do not specify the S region targets of CSR. By contrast, the combinatorial H3K9acS10ph modification specifically marks the S regions set to recombine and directly recruits 14-3-3 adaptors for AID stabilization there. Inhibition of the enzymatic activity of GCN5 and PCAF histone acetyltransferases reduces H3K9acS10ph in S regions, 14-3-3 and AID stabilization, and CSR. Thus, H3K9acS10ph is a histone code that is “written” specifically in S regions and is “read” by 14-3-3 adaptors to target AID for CSR as an important biological outcome.

Aging is associated with a decline in immune function, increasing the frequency and severity of infection in the elderly. We have previously shown that Asparagine (N) – linked protein glycosylation is a critical negative regulator of T cell immunity in both mice and humans. Here we report N-glycan branching in T cells increases with age, leading to T cell hypo-activity and increased susceptibility to infection. Reducing N-glycan branching rejuvenates T cell activation, proliferation and pro-inflammatory TH17 over anti-inflammatory Treg differentiation in aged T cells. Susceptibility of aged mice to Salmonellae typhimurium invasion/dissemination was reduced by lowering N-glycan branching. A critical metabolic precursor of N-glycosylation and branching is N-acetylglucosamine (GlcNAc), a common amino sugar that is part of the regular human diet. GlcNAc is endogenous to human serum, increases with age and correlates with N-glycan branching in T cells. T cell specific deletion of N-acetylglucosamine kinase, thereby blocking salvage of GlcNAc into N-glycans, reduces branching in aged T cells and rejuvenates T cell activation. Collectively, our results suggest that age-dependent increases in N-glycan branching, via increased supply of GlcNAc, impairs T cell immunity in the elderly. Therapeutic inhibition of N-glycan branching may provide a novel mechanism to rejuvenate T cell responses and reduce infection risk in the elderly.

Stroke is a major cause of death and disability, with very limited treatment option. Cell-based therapies have emerged as potential treatments for stroke. Indeed, studies have shown that transplantation of neural stem cells (NSCs) exerts functional benefits in stroke models. However, graft survival and integration with the host remain pressing concerns with cell-based treatments. The current study set out to investigate those very issues using a human NSC line, NSI-566RSC, in a rat model of ischemic stroke induced by transient occlusion of the middle cerebral artery. Seven days after stroke surgery, those animals that showed significant motor and neurological impairments were randomly assigned to receive NSI-566RSC intracerebral transplants at two sites within the striatum at three different doses: group A (0 cells/µl), group B (5,000 cells/µl), group C (10,000 cells/µl), and group D (20,000 cells/µl). Weekly behavioral tests, starting at seven days and continued up to 8 weeks after transplantation, revealed dose-dependent recovery from both motor and neurological deficits in transplanted stroke animals. Eight weeks after cell transplantation, immunohistochemical investigations via hematoxylin and eosin staining revealed infarct size was similar across all groups. To identify the cell graft, and estimate volume, immunohistochemistry was performed using two human-specific antibodies: one to detect all human nuclei (HuNu), and another to detect human neuron-specific enolase (hNSE). Surviving cell grafts were confirmed in 10/10 animals of group B, 9/10 group C, and 9/10 in group D. hNSE and HuNu staining revealed similar graft volume estimates in transplanted stroke animals. hNSE-immunoreactive fibers were also present within the corpus callosum, coursing in parallel with host tracts, suggesting a propensity to follow established neuroanatomical features. Despite absence of reduction in infarct volume, NSI-566RSC transplantation produced behavioral improvements possibly via robust engraftment and neuronal differentiation, supporting the use of this NSC line for stroke therapy.