Burden In Part Research Articles

Short Telomeres Associate with Hyperphosphorylated Tau Burden in Primary Age‐Related Tauopathy

AbstractBackgroundPrimary age‐related tauopathy (PART) is characterized by neuropathological hyperphosphorylated tau burden (p‐tau) in the absence of significant amyloid pathology. Aging is a major risk factor for p‐tau that is generally defined chronologically in years since birth. Telomeres shorten with age and various sources of DNA damage and thus telomere lengths (TL) provide an alternative measure of biological age. Additionally, DNA methylation (DNAm) changes over time and may contribute to changes in TL. Together, we hypothesize that shorter mean TL will be associated with increased risk of p‐tau burden and that this process may be mediated by DNAm.MethodWe extracted DNA from frontal cortex of 113 individuals (Age=87.3+9.3; 37% Female) that met neuropathological criteria for definite PART. We measured mean TL using qPCR to determine the copy number of telomere repeat DNA in comparison to a single copy gene. The assays were performed in a blinded fashion, and each sample was measured using two different amounts of input DNA to ensure linearity. We also measured bisulfite‐converted DNA methylation using the Illumina MethylationEPIC BeadChip Kit for ∼850K CpGs. P‐tau burden was measured in medial temporal cortex (entorhinal cortex and hippocampus proper) using an Aperio Digital Pathology Slide Scanner. Linear regression related TL to p‐tau burden, adjusting for age. We used eWAS to relate methylation to TL. Lastly, non‐parametric bootstrapping using the mediation package in R was used to evaluate whether TL association with p‐tau burden may be mediated by DNAm.ResultShorter TL was significantly associated with increased p‐tau burden (B=‐0.28; p=‐.003), including adjustment for age (B=0.003; p=0.003). eWAS identified six CpG sites significantly associated with TL (all q<0.05). Causal mediation analyses identified that two of these CpGs partially mediate the association between TL length and p‐tau burden: 32.5% proportion mediated by cg08701686 (UNC5D) and 48.6% proportion mediated by cg24533059 (near IFNGR1 and OLIG3).ConclusionShorter TL is associated with increased p‐tau pathological burden in PART and may be mediated in part by DNAm at particular loci. These findings support the concept that biological aging, as measured with TL and DNAm, may contribute to tauopathy beyond chronological age effects.

BSCI-18 ESTROGEN-DEPLETION DECREASES PROGRESSION OF ER¯ BRAIN METASTASES BY PROMOTING AN ANTI-TUMORAL LOCAL IMMUNE RESPONSE

We have shown that 17-β-Estradiol (E2) promotes brain metastasis (BM) of estrogen receptor negative (ER¯) BC cells by inducing neuroinflammatory ER+ astrocytes in the brain niche to secrete pro-metastatic factors critical for early brain colonization. E2-depletion prevented brain colonization of human xenografts (MDA231BR/NSG) and syngeneic (E0711/C57Bl6, 4T1/Balb-c) ER¯ models. Yet, whether E2-depletion can be used to decrease progression of established BM and how E2-dependent modulation of brain immune response contributes to the pro-metastatic effects of E2 remains unclear. To assess whether E2-depletion could decrease BM progression in a model that mimics standard of care for BM, E0771-GFP-luc cells were injected intracardially in syngeneic ovariectomized (OVX)-female C57Bl6 mice supplemented with E2. Seven days after injection (when micrometastases are established), mice received a single 15Gy dose brain irradiation and were randomized to continue receiving E2, E2 withdrawal (E2WD) or E2WD plus the aromatase-inhibitor letrozole (EWD+LET). Endpoint BM (but not systemic metastases) were significantly decreased in E2WD+Letrozole treated mice as compared to E2-treated mice. This effect was abolished when E0711 cells were injected in severely immunocompromised NSG mice or in the absence of brain irradiation, suggesting EWD+LET decreases BM progression through boosting radiation-induced anti-tumor immunity. Accordingly, there were no differences in BM progression in E2, EWD or E2WD+let treated mice in a xenograft model (F2-7 TNBC cells) in NSG mice, even in the presence of brain irradiation. Brain immune-profiling of brain irradiated E2, EWD and EWD+Let C57BL6 mice carrying E0771 BMs shows that brains of EWD+LET-treated mice had a significantly lower fraction of CD4 T cells and an increase in CD8 T cells, suggesting that EWD+letrozole decrease brain metastatic burden in part through modulation of T cells. These results suggest E2-depletion therapies could be used in combination with brain irradiation to decrease progression of BMs and promote an anti-tumoral immune response.

Somatosensory behavioral alterations in a NGF-induced persistent low back pain model

Low back pain (LBP) is a major global burden in part due to the underlying pathophysiological mechanisms being poorly understood. A LBP rat model involving two injections of nerve growth factor (NGF, an endogenous pain-related neurotrophin) into trunk musculature was recently developed. Additional behavioral work in this NGF-LBP rat model is required to better characterize local and remote somatosensory alterations related to NGF-induced peripheral and central sensitization. This work characterizes the time-dependent development of hypersensitivity to trunk and hindpaw cutaneous mechanical stimulation and deep muscle mechanical hyperalgesia in adult male Sprague-Dawley rats (n = 6/group). Behavioral assays were performed at baseline (Day 0, D0), D2, D5 (pre- and 4 h post-2nd NGF or control injection), D7, D10, and D14 in NGF and control groups. Trunk and hindpaw cutaneous mechanical hypersensitivity were tested using von Frey filaments. Deep trunk mechanical hyperalgesia was determined using a small animal algometer. NGF rats demonstrated increased cutaneous sensitivity to ipsilateral trunk mechanical stimuli at D7, D10, and D14. NGF rats also demonstrated ipsilateral deep mechanical hyperalgesia on D2, D5 + 4 h, D7, D10, and D14. Cutaneous hypersensitivity was delayed compared to deep hyperalgesia in NGF rats. No additional sensory changes were noted. Together, these results indicate that male mechanical somatosensory changes develop primarily locally in the ipsilateral trunk following unilateral NGF injections. These findings contrast with a previous report in female rats using this NGF-LBP model showing more widespread (bilateral) hyperalgesia and remote mechanical hypersensitivity. Future studies will examine potential sex-related pain behavioral differences in the NGF model.

Cognitive decline associated with pathological burden in primary age-related tauopathy

IntroductionPrimary age-related tauopathy (PART) is a neuropathological diagnosis characterized by tau neurofibrillary tangles (NFTs) in the absence of amyloid plaque pathology. Although most individuals over 50 years of age have evidence of NFTs, the clinical and cognitive consequences of PART are not known. MethodsWe evaluated 226 neuropathologically confirmed PART cases from the National Alzheimer's Coordinating Center database who participated in a total of 846 longitudinal neuropsychological assessments from the Alzheimer's Disease Center program‘s Uniform Data Set. Mixed-effects statistical models tested whether cognitive decline was associated with Braak stage NFT burden. ResultsHigher stages of NFT burden in PART, with no evidence or minimal evidence of amyloid pathology, were associated with more rapid decline on tasks involving episodic and semantic memory along with tests of processing speed and attention. DiscussionWe conclude that PART has cognitive consequences that should be considered in the context of emerging tau-targeted therapies in age-associated neurodegenerative diseases.

Uraemia: an unrecognized driver of central neurohumoral dysfunction in chronic kidney disease?

Chronic kidney disease (CKD) carries a large cardiovascular burden in part due to hypertension and neurohumoral dysfunction - manifesting as sympathetic overactivity, baroreflex dysfunction and chronically elevated circulating vasopressin. Alterations within the central nervous system (CNS) are necessary for the expression of neurohumoral dysfunction in CKD; however, the underlying mechanisms are poorly defined. Uraemic toxins are a diverse group of compounds that accumulate as a direct result of renal disease and drive dysfunction in multiple organs, including the brain. Intensive haemodialysis improves both sympathetic overactivity and cardiac baroreflex sensitivity in renal failure patients, indicating that uraemic toxins participate in the maintenance of autonomic dysfunction in CKD. In rodents exposed to uraemia, immediate early gene expression analysis suggests upregulated activity of not only pre-sympathetic but also vasopressin-secretory nuclei. We outline several potential mechanisms by which uraemia might drive neurohumoral dysfunction in CKD. These include superoxide-dependent effects on neural activity, depletion of nitric oxide and induction of low-grade systemic inflammation. Recent evidence has highlighted superoxide production as an intermediate for the depolarizing effect of some uraemic toxins on neuronal cells. We provide preliminary data indicating augmented superoxide production within the hypothalamic paraventricular nucleus in the Lewis polycystic kidney rat, which might be important for mediating the neurohumoral dysfunction exhibited in this CKD model. We speculate that the uraemic state might serve to sensitize the central actions of other sympathoexcitatory factors, including renal afferent nerve inputs to the CNS and angiotensin II, by way of recruiting convergent superoxide-dependent and pro-inflammatory pathways.

The Influence of a High‐Fat Dietary Environment in the Fetal Period on Postnatal Metabolic and Immune Function

Few reports show whether a high-fat (HF) dietary environment in the fetal period affects immune function or the development of lifestyle-related disease at maturity. We examined the influence of an HF dietary environment in the fetal period on postnatal metabolic and immune function. A total of 16 pregnant mice were given control (CON) diet and 16 were given HF diet in the gestational period, from mating to delivery. After delivery lactating mice were given either CON or HF diet, resulting in four groups. After weaning, the offspring mice were given the same diet that their mothers received during lactation. HF dietary intake in the postnatal period increased fat pad weights, serum glucose, and leptin levels. An HF diet in the fetal period resulted in fewer splenic lymphocytes, a thinner thymic cortex, and impaired antigen-specific immune reactions. Furthermore, tumor necrosis factor (TNF)-alpha production and serum triglyceride levels were elevated in the fetal HF group. In addition, the HF-HF group showed a consistent decrease in ovalbumin (OVA)-specific IgG and elevation of IgE, associated with advanced fatty changes in the liver. Results from this study suggest that HF environment during the fetal period induces epigenetic propensity toward obesity and immunological burden in part due to increased adipose tissue mass, significant reduction in the number of immune cells and decreased activities of immune cells.

Suppressing effects of dietary supplementation of soybean trypsin inhibitor on spontaneous, experimental and peritoneal disseminated metastasis in mouse model.

The modifying effects of a Kunitz trypsin inhibitor (KTI) and a Bowman-Birk trypsin inhibitor (BBI), purified from soybean trypsin inhibitor, as dietary supplements on experimental and spontaneous pulmonary metastasis of murine Lewis lung carcinoma 3LL cells as well as peritoneal disseminated metastasis model in human ovarian cancer HRA cells were investigated in i.v., s.c. and i.p. injection models in mice. Seven groups of female C57BL/6 or nude mice were fed a basal diet (control group) or the basal diet supplemented with KTI or BBI (5, 15, or 50 g/kg). Here we show that, in an in vivo spontaneous metastasis assay, the diet supplementation with KTI (15 and 50 g/kg), but not with BBI, for 28 days immediately after s.c. tumor cell inoculation significantly inhibited the formation of lung metastasis in C57BL/6 mice in a dose-dependent manner. The inhibition of lung metastasis was not due to direct antitumor effects of KTI. In an in vivo experimental metastasis assay, the diet supplementation with KTI or BBI for 21 days after i.v. tumor cell inoculation did not reduce the number of lung tumor colonies. In addition, KTI (15 or 50 g/kg) treatment in a peritoneal disseminated metastasis model of HRA cells resulted in a 40% reduction in total tumor burden when compared with control animals. Immunoblot analysis revealed that KTI specifically reduced expression of uPA protein as well as phosphorylation of MAP kinase and PI3 kinase proteins in the cells stimulated with agonists (G-CSF for 3LL cells or TGF-beta1 for HRA cells). These results suggest that dietary supplementation of KTI more efficiently regulates the mechanism involved in the entry into vascular circulation of tumor cells (intravasation) than in extravasation during the metastatic process. KTI treatment may also be beneficial for ovarian cancer patients with or at risk for peritoneal disseminated metastasis; it greatly reduces tumor burden in part by inhibiting phosphorylation of MAP kinase and PI3 kinase, leading to suppression of uPA expression.