Summary Cytoplasmic accumulation of TDP-43 is a disease hallmark for many cases of amyotrophic lateral sclerosis (ALS), associated with a neuroinflammatory cytokine profile related to upregulation of nuclear factor κB (NF-κB) and type I interferon (IFN) pathways. Here we show that this inflammation is driven by the cytoplasmic DNA sensor cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS) when TDP-43 invades mitochondria and releases DNA via the permeability transition pore. Pharmacologic inhibition or genetic deletion of cGAS and its downstream signaling partner STING prevents upregulation of NF-κB and type I IFN induced by TDP-43 in induced pluripotent stem cell (iPSC)-derived motor neurons and in TDP-43 mutant mice. Finally, we document elevated levels of the specific cGAS signaling metabolite cGAMP in spinal cord samples from patients, which may be a biomarker of mtDNA release and cGAS/STING activation in ALS. Our results identify mtDNA release and cGAS/STING activation as critical determinants of TDP-43-associated pathology and demonstrate the potential for targeting this pathway in ALS.

The neuropathological substrate of dementia in patients with Parkinson's disease is still under debate, particularly in patients with insufficient alternate neuropathology for other degenerative dementias. In patients with pure Lewy body Parkinson's disease, previous post-mortem studies have shown that dopaminergic and cholinergic regulatory projection systems degenerate, but the exact pathways that may explain the development of dementia in patients with Parkinson's disease remain unclear. Studies in rodents suggest that both the mesocorticolimbic dopaminergic and septohippocampal cholinergic pathways may functionally interact to regulate certain aspects of cognition, however, whether such an interaction occurs in humans is still poorly understood. In this study, we performed stereological analyses of the A9 and A10 dopaminergic neurons and Ch1, Ch2 and Ch4 cholinergic neurons located in the basal forebrain, along with an assessment of α-synuclein pathology in these regions and in the hippocampus of six demented and five non-demented patients with Parkinson's disease and five age-matched control individuals with no signs of neurological disease. Moreover, we measured choline acetyltransferase activity in the hippocampus and frontal cortex of eight demented and eight non-demented patients with Parkinson's disease, as well as in the same areas of eight age-matched controls. All patients with Parkinson's disease exhibited a similar 80-85% loss of pigmented A9 dopaminergic neurons, whereas patients with Parkinson's disease dementia presented an additional loss in the lateral part of A10 dopaminergic neurons as well as Ch4 nucleus basalis neurons. In contrast, medial A10 dopaminergic neurons and Ch1 and Ch2 cholinergic septal neurons were largely spared. Despite variable Ch4 cell loss, cortical but not hippocampal cholinergic activity was consistently reduced in all patients with Parkinson's disease, suggesting significant dysfunction in cortical cholinergic pathways before frank neuronal degeneration. Patients with Parkinson's disease dementia were differentiated by a significant reduction in hippocampal cholinergic activity, by a significant loss of non-pigmented lateral A10 dopaminergic neurons and Ch4 cholinergic neurons (30 and 55% cell loss, respectively, compared with neuronal preservation in control subjects), and by an increase in the severity of α-synuclein pathology in the basal forebrain and hippocampus. Overall, these results point to increasing α-synuclein deposition and hippocampal dysfunction in a setting of more widespread degeneration of cortical dopaminergic and cholinergic pathways as contributing to the dementia occurring in patients with pure Parkinson's disease. Furthermore, our findings support the concept that α-synuclein deposition is associated with significant neuronal dysfunction in the absence of frank neuronal loss in Parkinson's disease.

AbstractMacrophages are key target cells for HIV-1. HIV-1BaL induced a subset of interferon-stimulated genes in monocyte-derived macrophages (MDMs), which differed from that in monocyte-derived dendritic cells and CD4 T cells, without inducing any interferons. Inhibition of type I interferon induction was mediated by HIV-1 inhibition of interferon-regulated factor (IRF3) nuclear translocation. In MDMs, viperin was the most up-regulated interferon-stimulated genes, and it significantly inhibited HIV-1 production. HIV-1 infection disrupted lipid rafts via viperin induction and redistributed viperin to CD81 compartments, the site of HIV-1 egress by budding in MDMs. Exogenous farnesol, which enhances membrane protein prenylation, reversed viperin-mediated inhibition of HIV-1 production. Mutagenesis analysis in transfected cell lines showed that the internal S-adenosyl methionine domains of viperin were essential for its antiviral activity. Thus viperin may contribute to persistent noncytopathic HIV-1 infection of macrophages and possibly to biologic differences with HIV-1–infected T cells.

Amyotrophic lateral sclerosis is a rapidly progressing fatal neurodegenerative disease characterized by the presence of protein inclusions within affected motor neurons. Endoplasmic reticulum stress leading to apoptosis was recently recognized to be an important process in the pathogenesis of sporadic human amyotrophic lateral sclerosis as well as in transgenic models of mutant superoxide dismutase 1-linked familial amyotrophic lateral sclerosis. Endoplasmic reticulum stress occurs early in disease, indicating a critical role in pathogenesis, and involves upregulation of an important endoplasmic reticulum chaperone, protein disulphide isomerase. We aimed to investigate the involvement of protein disulphide isomerase in endoplasmic reticulum stress induction, protein aggregation, inclusion formation and toxicity in amyotrophic lateral sclerosis. Motor neuron-like NSC-34 cell lines were transfected with superoxide dismutase 1 and protein disulphide isomerase encoding vectors and small interfering RNA, and examined by immunocytochemistry and immunoblotting. Expression of mutant superoxide dismutase 1 induced endoplasmic reticulum stress, predominantly in cells bearing mutant superoxide dismutase 1 inclusions but also in a proportion of cells expressing mutant superoxide dismutase 1 without visible inclusions. Over-expression of protein disulphide isomerase decreased mutant superoxide dismutase 1 aggregation, inclusion formation, endoplasmic reticulum stress induction and toxicity, whereas small interfering RNA targeting protein disulphide isomerase increased mutant superoxide dismutase 1 inclusion formation, indicating a protective role for protein disulphide isomerase against superoxide dismutase 1 misfolding. Aberrant modification of protein disulphide isomerase by S-nitrosylation of active site cysteine residues has previously been shown as an important process in neurodegeneration in Parkinson's and Alzheimer's disease brain tissue, but has not been described in amyotrophic lateral sclerosis. Using a biotin switch assay, we detected increased levels of S-nitrosylated protein disulphide isomerase in transgenic mutant superoxide dismutase 1 mouse and human sporadic amyotrophic lateral sclerosis spinal cord tissues. Hence, despite upregulation, protein disulphide isomerase is also functionally inactivated in amyotrophic lateral sclerosis, which may prevent its normal protective function and contribute to disease. We also found that a small molecule mimic of the protein disulphide isomerase active site, (+/-)-trans-1,2-bis(mercaptoacetamido)cyclohexane, protected against mutant superoxide dismutase 1 inclusion formation. These studies reveal that endoplasmic reticulum stress is important in the formation of mutant superoxide dismutase 1 inclusions, and protein disulphide isomerase has an important function in ameliorating mutant superoxide dismutase 1 aggregation and toxicity. Functional inhibition of protein disulphide isomerase by S-nitrosylation may contribute to pathophysiology in both mutant superoxide dismutas...

IMPORTANCE Neuroinflammation appears to be a key modulator of disease progression in amyotrophic lateral sclerosis (ALS) and thereby a promising therapeutic target. The CD4 + Foxp3 + regulatory T-cells (Tregs) infiltrating into the central nervous system suppress neuroinflammation and promote the activation of neuroprotective microglia in mouse models of ALS. To our knowledge, the therapeutic association of host Treg expansion with ALS progression has not been studied in vivo.OBJECTIVE To assess the role of Tregs in regulating the pathophysiology of ALS in humans and the therapeutic outcome of increasing Treg activity in a mouse model of the disease. DESIGN, SETTING, AND PARTICIPANTS This prospective multicenter human and animal study was performed in hospitals, outpatient clinics, and research institutes. Clinical and function assessment, as well as immunological studies, were undertaken in 33 patients with sporadic ALS, and results were compared with 38 healthy control participants who were consecutively recruited from the multidisciplinary ALS clinic at Westmead Hospital between February 1, 2013, and December 31, 2014. All data analysis on patients with ALS was undertaken between January 2015 and December 2016. Subsequently, we implemented a novel approach to amplify the endogenous Treg population using peripheral injections of interleukin 2/interleukin 2 monoclonal antibody complexes (IL-2c) in transgenic mice that expressed mutant superoxide dismutase 1 (SOD1), a gene associated with motor neuron degeneration. MAIN OUTCOMES AND MEASURESIn patients with ALS, Treg levels were determined and then correlated with disease progression. Circulating T-cell populations, motor neuron size, glial cell activation, and T-cell and microglial gene expression in spinal cords were determined in SOD1 G93A mice, as well as the association of Treg amplification with disease onset and survival time in mice. RESULTSThe cohort of patients with ALS included 24 male patients and 9 female patients (mean [SD] age at assessment, 58.9 [10.9] years). There was an inverse correlation between total Treg levels (including the effector CD45RO + subset) and rate of disease progression (R = −0.40, P = .002). Expansion of the effector Treg population in the SOD1 G93A mice was associated with a significant slowing of disease progression, which was accompanied by an increase in survival time (IL-2c-treated mice: mean [SD], 160.6 [10.8] days; control mice: mean [SD], 144.9 [10.6] days; P = .003). Importantly, Treg expansion was associated with preserved motor neuron soma size and marked suppression of astrocytic and microglial immunoreactivity in the spinal cords of SOD1 G93A mice, as well as elevated neurotrophic factor gene expression in spinal cord and peripheral nerves. CONCLUSIONS AND RELEVANCE These findings establish a neuroprotective effect of Tregs, possibly mediated by suppression of toxic neuroinflammation in the central nervous system. Strategies aimed at enhancing the Treg population and neuroprotective activity from the periphery may...

In HIV infection, dendritic cells (DCs) may play multiple roles, probably including initial HIV uptake in the anogenital mucosa, transport to lymph nodes, and subsequent transfer to T cells. The effects of HIV-1 on DC maturation are controversial, with several recent conflicting reports in the literature. In this study, microarray studies, confirmed by real-time PCR, demonstrated that the genes encoding DC surface maturation markers were among the most differentially expressed in monocyte-derived dendritic cells (MDDCs), derived from human blood, treated with live or aldrithriol-2-inactivated HIV-1BaL. These effects translated to enhanced cell surface expression of these proteins but differential expression of maturation markers was only partial compared with the effects of a conventional potent maturation stimulus. Such partially mature MDDCs can be converted to fully mature cells by this same potent stimulus. Furthermore, live HIV-1 stimulated greater changes in maturation marker surface expression than aldrithriol-2-inactivated HIV-1 and this enhanced stimulation by live HIV-1 was mediated via CCR5, thus suggesting both viral replication-dependent and -independent mechanisms. These partially mature MDDCs demonstrated enhanced CCR7-mediated migration and are also able to stimulate interacting T cells in a MLR, suggesting DCs harboring HIV-1 might prepare CD4 lymphocytes for transfer of HIV-1. Increased maturation marker surface expression was also demonstrated in native DCs, ex vivo Langerhans cells derived from human skin. Thus, HIV initiates maturation of DCs which could facilitate subsequent enhanced transfer to T cells.

Dysfunctional dopaminergic (DAergic) neurotransmission between the substantia nigra pars compacta (SNc) and the dorsal striatum (the nigrostriatal pathway) causes several prominent movement disorders (e.g. the motor symptoms of Parkinson's disease, dystonias and dyskinesias). Both too much and too little DA signalling can be problematic and nigrostriatal DAergic transmission is maintained at normal levels by several homeostatic mechanisms acting over timescales of milliseconds to weeks: e.g. binding of DA to tyrosine 3-monooxygenase (EC 1.14.16.2) (tyrosine Received November 1, 2010; revised manuscript received December 13, 2010; accepted December 14, 2010. Address correspondence and reprint requests to T. D. Aumann, Florey Neuroscience Institutes, The University of Melbourne, Parkville, Victoria, Australia 3010. E-mail: tim.aumann@florey.edu.auAbbreviations used: D2R, D 2 dopamine receptor; DA, dopamine; EGF, epidermal growth factor; FGF, fibroblast growth factor; GDNF, glial cellderived neurotrophic factor; GFP, green fluorescent protein; PAGE, polyacrylamide gel electrophoresis; PBS, phosphate-buffered saline; RRF, retrorubral field; SDS, sodium dodecyl sulfate; SK, small-conductance, Ca 2+ -activated potassium; SNc, substantia nigra pars compacta; TH, tyrosine hydroxylase; TTX, tetrodotoxin; VTA, ventral tegmental area. AbstractStriatal delivery of dopamine (DA) by midbrain substantia nigra pars compacta (SNc) neurons is vital for motor control and its depletion causes the motor symptoms of Parkinson's disease. While membrane potential changes or neuronal activity regulates tyrosine hydroxylase (TH, the rate limiting enzyme in catecholamine synthesis) expression in other catecholaminergic cells, it is not known whether the same occurs in adult SNc neurons. We administered drugs known to alter neuronal activity to mouse SNc DAergic neurons in various experimental preparations and measured changes in their TH expression. In cultured midbrain neurons, blockade of action potentials with 1 lM tetrodotoxin decreased TH expression beginning around 20 h later (as measured in real time by green fluorescent protein (GFP) expression driven off TH promoter activity). By contrast, partial blockade of small-conductance, Ca 2+ -activated potassium channels with 300 nM apamin increased TH mRNA and protein between 12 and 24 h later in slices of adult midbrain. Twoweek infusions of 300 nM apamin directly to the adult mouse midbrain in vivo also increased TH expression in SNc neurons, measured immunohistochemically. Paradoxically, the number of TH immunoreactive (TH+) SNc neurons decreased in these animals. Similar in vivo infusions of drugs affecting other ion-channels and receptors (L-type voltage-activated Ca 2+ channels, GABA A receptors, high K + , DA receptors) also increased or decreased cellular TH immunoreactivity but decreased or increased, respectively, the number of TH+ cells in SNc. We conclude that in adult SNc neurons: (i) TH expression is activity-dependent and begins to change 20 h following sustained chang...

Relaxin-3 is a neuropeptide that is abundantly expressed by discrete brainstem neuron populations that broadly innervate forebrain areas rich in the relaxin-3 G-protein-coupled-receptor, RXFP3. Acute and subchronic central administration of synthetic relaxin-3 or an RXFP3-selective agonist peptide, R3/I5, increase feeding and body weight in rats. Intrahypothalamic injection of relaxin-3 also increases feeding. In this study, we developed a recombinant adeno-associated virus 1/2 (rAAV1/2) vector that drives expression and constitutive secretion of bioactive R3/I5 and assessed the effect of intrahypothalamic injections on daily food intake and body weight gain in adult male rats over 8 weeks. In vitro testing revealed that the vector rAAV1/2-fibronectin (FIB)-R3/I5 directs the constitutive secretion of bioactive R3/I5 peptide. Bilateral injection of rAAV1/2-FIB-R3/I5 vector into the paraventricular nucleus produced an increase in daily food intake and body weight gain (P<0.01, ~23%, respectively), relative to control treatment. In a separate cohort of rats, quantitative polymerase chain reaction analysis of hypothalamic mRNA revealed strong expression of R3/I5 transgene at 3 months post-rAAV1/2-FIB-R3/I5 infusion. Levels of mRNA transcripts for the relaxin-3 receptor RXFP3, the hypothalamic 'feeding' peptides neuropeptide Y, AgRP and POMC, and the reproductive hormone, GnRH, were all similar to control, whereas vasopressin and oxytocin (OT) mRNA levels were reduced by ~25% (P=0.051) and ~50% (P<0.005), respectively, in rAAV1/2-FIB-R3/I5-treated rats (at 12 weeks, n=9/8 rats per group). These data demonstrate for the first time that R3/I5 is effective in modulating feeding in the rat by chronic hypothalamic RXFP3 activation and suggest a potential underlying mechanism involving altered OT signalling. Importantly, there was no desensitization of the feeding response over the treatment period and no apparent deleterious health effects, indicating that targeting the relaxin-3-RXFP3 system may be an effective long-term therapy for eating disorders.