Sex-specific effects of microbiome perturbations on cerebral Aβ amyloidosis and microglia phenotypes.

We demonstrated that an antibiotic cocktail (ABX)-perturbed gut microbiome is associated with reduced amyloid-β (Aβ) plaque pathology and astrogliosis in the male amyloid precursor protein (APP)SWE /presenilin 1 (PS1)ΔE9 transgenic model of Aβ amyloidosis. We now show that in an independent, aggressive APPSWE/PS1L166P (APPPS1-21) mouse model of Aβ amyloidosis, an ABX-perturbed gut microbiome is associated with a reduction in Aβ pathology and alterations in microglial morphology, thus establishing the generality of the phenomenon. Most importantly, these latter alterations occur only in brains of male mice, not in the brains of female mice. Furthermore, ABX treatment lead to alterations in levels of selected microglial expressed transcripts indicative of the "M0" homeostatic state in male but not in female mice. Finally, we found that transplants of fecal microbiota from age-matched APPPS1-21 male mice into ABX-treated APPPS1-21 male restores the gut microbiome and partially restores Aβ pathology and microglial morphology, thus demonstrating a causal role of the microbiome in the modulation of Aβ amyloidosis and microglial physiology in mouse models of Aβ amyloidosis

Human Neural Stem Cells Survive Long Term in the Midbrain of Dopamine-Depleted Monkeys After GDNF Overexpression and Project Neurites Toward an Appropriate Target

Transplanted multipotent human fetal neural stem cells (hfNSCs) significantly improved the function of parkinsonian monkeys in a prior study primarily by neuroprotection, with only 3%–5% of cells expressing a dopamine (DA) phenotype. In this paper, we sought to determine whether further manipulation of the neural microenvironment by overexpression of a developmentally critical molecule, glial cell-derived neurotrophic factor (GDNF), in the host striatum could enhance DA differentiation of hfNSCs injected into the substantia nigra and elicit growth of their axons to the GDNF-expressing target. hfNSCs were transplanted into the midbrain of 10 green monkeys exposed to 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine. GDNF was delivered concomitantly to the striatum via an adeno-associated virus serotype 5 vector, and the fate of grafted cells was assessed after 11 months. Donor cells remained predominantly within the midbrain at the injection site and sprouted numerous neurofilament-immunoreactive fibers that appeared to course rostrally toward the striatum in parallel with tyrosine hydroxylase-immunoreactive fibers from the host substantia nigra but did not mature into DA neurons. This work suggests that hfNSCs can generate neurons that project long fibers in the adult primate brain. However, in the absence of region-specific signals and despite GDNF overexpression, hfNSCs did not differentiate into mature DA neurons in large numbers. It is encouraging, however, that the adult primate brain appeared to retain axonal guidance cues. We believe that transplantation of stem cells, specifically instructed ex vivo to yield DA neurons, could lead to reconstruction of some portion of the nigrostriatal pathway and prove beneficial for the parkinsonian condition

NPT088 reduces both amyloid-b and tau pathologies in transgenic mice

Introduction: Alzheimer’s disease (AD) is characterized by appearance of both extracellular senile plaques and intracellular neurofibrillary tangles, comprised of aggregates of misfolded amyloid-b (Ab) and hyper-phosphorylated tau, respectively. In a previous study, we demonstrated that g3p, a capsid protein from bacteriophage M13, binds to and remodels misfolded aggregates of proteins that assume an amyloid conformation. We engineered a fusion protein (“NPT088”) consisting of the active fragment of g3p and human-IgG1-Fc. Methods: Aged Tg2576 mice or rTg4510 mice received NPT088 weekly via IP injection. Cognitive and/or functional motor endpoints were monitored during dosing. Pathology was quantified biochemically and immunohistochemically. Results: NPT088-lowered Ab plaque and improved cognitive performance of aged Tg2576 mice. Moreover, NPT088 reduced phospho-tau pathology, reduced brain atrophy, and improved cognition in rTg4510 mice. Discussion: These observations establish NPT088 as a novel therapeutic approach and potential drug class that targets both Ab and tau, the hallmark pathologies of AD

Increased Intestinal Permeability Correlates with Sigmoid Mucosa alpha-Synuclein Staining and Endotoxin Exposure Markers in Early Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder of aging. The pathological hallmark of PD is neuronal inclusions termed Lewy bodies whose main component is alpha-synuclein protein. The finding of these Lewy bodies in the intestinal enteric nerves led to the hypothesis that the intestine might be an early site of PD disease in response to an environmental toxin or pathogen. One potential mechanism for environmental toxin(s) and proinflammatory luminal products to gain access to mucosal neuronal tissue and promote oxidative stress is compromised intestinal barrier integrity. However, the role of intestinal permeability in PD has never been tested. We hypothesized that PD subjects might exhibit increased intestinal permeability to proinflammatory bacterial products in the intestine. To test our hypothesis we evaluated intestinal permeability in subjects newly diagnosed with PD and compared their values to healthy subjects. In addition, we obtained intestinal biopsies from both groups and used immunohistochemistry to assess bacterial translocation, nitrotyrosine (oxidative stress), and alpha-synuclein. We also evaluated serum markers of endotoxin exposure including LPS binding protein (LBP). Our data show that our PD subjects exhibit significantly greater intestinal permeability (gut leakiness) than controls. In addition, this intestinal hyperpermeability significantly correlated with increased intestinal mucosa staining for E. coli bacteria, nitrotyrosine, and alpha-synuclein as well as serum LBP levels in PD subjects. These data represent not only the first demonstration of abnormal intestinal permeability in PD subjects but also the first correlation of increased intestinal permeability in PD with intestinal alpha-synuclein (the hallmark of PD), as well as staining for gram negative bacteria and tissue oxidative stress. Our study may thus shed new light on PD pathogenesis as well as provide a new method for earlier diagnosis of PD and suggests potential therapeutic targets in PD subjects.Clinicaltrials.gov NCT01155492

Future of Probiotics and Prebiotics and the Implications for Early Career Researchers

The opportunities in the fields of probiotics and prebiotics to a great degree stem from what we can learn about how they influence the microbiota and interact with the host. We discuss recent insights, cutting-edge technologies and controversial results from the perspective of early career researchers innovating in these areas. This perspective emerged from the 2019 meeting of the International Scientific Association for Probiotics and Prebiotics - Student and Fellows Association (ISAPP-SFA). Probiotic and prebiotic research is being driven by genetic characterization and modification of strains, state-of-the-art in vitro, in vivo, and in silico techniques designed to uncover the effects of probiotics and prebiotics on their targets, and metabolomic tools to identify key molecules that mediate benefits on the host. These research tools offer unprecedented insights into the functionality of probiotics and prebiotics in the host ecosystem. Young scientists need to acquire these diverse toolsets, or form inter-connected teams to perform comprehensive experiments and systematic analysis of data. This will be critical to identify microbial structure and co-dependencies at body sites and determine how administered probiotic strains and prebiotic substances influence the host. This and other strategies proposed in this review will pave the way for translating the health benefits observed during research into real-life outcomes. Probiotic strains and prebiotic products can contribute greatly to the amelioration of global issues threatening society. The intent of this article is to provide an early career researcher’s perspective on where the biggest opportunities lie to advance science and impact human health

Sex‐specific changes in amyloidosis and neuro‐immune modulation in response to alterations in the gut microbiome

BackgroundMicroglia, resident macrophages of CNS constantly screen the brain and engage in pathological processes by changing their morphology, expressing various antigens and become phagocytic. This activation causes the release of a wave of chemical mediators that promote the neuroinflammatory milieu. Thus, microglial homeostasis represents a highly plastic multifaceted response, finely tuned by the nature of the stimulus and the molecular repertoire involved. Studies from Sisodia lab have shown that antibiotic (ABX) mediated alterations of the gut microbiome in Thy1‐APPSwe.PS1L166Pmice (APPPS1‐21), resulted in a significant decrease in amyloidosis and altered microglial phenotypes in male mice. To investigate the influence of gut microbiome in modulating microglial function in a sex‐specific manner, we generated transgenic mice that would allow us to assess microglial RNA‐Protein networks and address the molecular mechanisms of CNS immunomodulation.MethodWe generated ‘Thy1‐APP.PS1‐RiboTag’ by crossing APPPS1‐21 mice to RiboTag mice wherein a CD11b promoter drives expression of ribosomal protein L10a (RpL10) that is fused to FLAG/EGFP at the amino‐terminus. Using our established protocol, we altered the microbiome of male and female mice (n=12) by orally gavaging them with ABX from day 14‐21, followed by low dose ABX in drinking water till they are sacrificed (7 wks). Vehicle treated mice were used as controls along with WT‐RiboTag mice. Immunoprecipitation of cortical homogenates with anti‐FLAG was performed to pull‐down actively translated mRNA and proteome in microglia following histopathology.ResultWe evaluated Aβ pathology and found that ABX‐treatment led to reduced amyloidosis in male mice with no significant changes in the female. Analysis of the mRNAs and the newly synthesized peptides resulted in a snapshot of the dynamic translational state of microglial ribosomes. We observed 21 upregulated and 22 downregulated proteins between the WT‐RiboTag and Th1‐APP.PS1‐RiboTag in male mice and 16 upregulated and 70 downregulated in female. Abx treatment resulted in upregulation of 39 and downregulation of 37 proteins in males while the females showed 51 and 9 respectively.ConclusionWe find marked differences in the mRNA and proteins associated with microglial phenotypes expressed in a sex‐specific manner as a function of changes in the gut microbiome.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163849/1/alz045243.pd

The gut-brain axis in Parkinson's disease : Possibilities for food-based therapies

Parkinson's disease (PD) is usually characterized by cardinal motor impairments. However, a range of non-motor symptoms precede the motor-phase and are major determinants for the quality of life. To date, no disease modifying treatment is available for PD patients. The gold standard therapy of levodopa is based on restoring dopaminergic neurotransmission, thereby alleviating motor symptoms, whereas non-motor symptoms remain undertreated. One of the most common non-motor symptoms is gastrointestinal dysfunction usually associated with alpha-synuclein accumulations and low-grade mucosal inflammation in the enteric nervous system. Accumulating evidence suggest that the enteric nervous system is involved in PD pathological progression towards the central nervous system. Moreover, different components of the gut could provide a central role in the gut-brain axis, which is as a bidirectional communicational system between the gastrointestinal tract and central nervous system. Dietary components might influence the gut-brain axis by altering microbiota composition or by affecting neuronal functioning in both the ENS and the CNS. This review gives a comprehensive overview of the evidences supporting the hypothesis that PD could initiate in the gut. We also consider how food-based therapies might then have an impact on PD pathology and/or improve non-motor as well as motor symptoms in PD

Colon dysregulation in methamphetamine self-administering HIV-1 transgenic rats.

The integrity and function of the gut is impaired in HIV-infected individuals, and gut pathogenesis may play a role in several HIV-associated disorders. Methamphetamine is a popular illicit drug abused by HIV-infected individuals. However, the effect of methamphetamine on the gut and its potential to exacerbate HIV-associated gut pathology is not known. To shed light on this scenario, we evaluated colon barrier pathology in a rat model of the human comorbid condition. Intestinal barrier integrity and permeability were assessed in drug-naïve Fischer 344 HIV-1 transgenic (Tg) and non-Tg rats, and in Tg and non-Tg rats instrumented with jugular cannulae trained to self-administer methamphetamine or serving as saline-yoked controls. Intestinal permeability was determined by measuring the urine content of orally gavaged sugars. Intestinal barrier integrity was evaluated by immunoblotting or immunofluorescence of colon claudin-1 and zonula occludens-1 (ZO-1), two major tight junction proteins that regulate gut epithelial paracellular permeability. Both non-Tg and Tg rats self-administered moderate amounts of methamphetamine. These amounts were sufficient to increase colon permeability, reduce protein level of claudin-1, and reduce claudin-1 and ZO-1 immunofluorescence in Tg rats relative to non-Tg rats. Methamphetamine decreased tight junction immunofluorescence in non-Tg rats, with a similar, but non-significant trend observed in Tg rats. However, the effect of methamphetamine on tight junction proteins was subthreshold to gut leakiness. These findings reveal that both HIV-1 proteins and methamphetamine alter colon barrier integrity, and indicate that the gut may be a pathogenic site for these insults