Gut microbial DL-endopeptidase alleviates Crohn's disease via the NOD2 pathway

Cell host & microbe

2022 Aug 25

Gao, J;Zhao, X;Hu, S;Huang, Z;Hu, M;Jin, S;Lu, B;Sun, K;Wang, Z;Fu, J;Weersma, RK;He, X;Zhou, H;
PMID: 36049483 | DOI: 10.1016/j.chom.2022.08.002

The pattern-recognition receptor NOD2 senses bacterial muropeptides to regulate host immunity and maintain homeostasis. Loss-of-function mutations in NOD2 are associated with Crohn's disease (CD), but how the variations in microbial factors influence NOD2 signaling and host pathology is elusive. We demonstrate that the Firmicutes peptidoglycan remodeling enzyme, DL-endopeptidase, increased the NOD2 ligand level in the gut and impacted colitis outcomes. Metagenomic analyses of global cohorts (n = 857) revealed that DL-endopeptidase gene abundance decreased globally in CD patients and negatively correlated with colitis. Fecal microbiota from CD patients with low DL-endopeptidase activity predisposed mice to colitis. Administering DL-endopeptidase, but not an active site mutant, alleviated colitis via the NOD2 pathway. Therapeutically restoring NOD2 ligands with a DL-endopeptidase-producing Lactobacillus salivarius strain or mifamurtide, a clinical analog of muramyl dipeptide, exerted potent anti-colitis effects. Our study suggests that the depletion of DL-endopeptidase contributes to CD pathogenesis through NOD2 signaling, providing a therapeutically modifiable target.

A tumour-resident Lgr5+ stem-cell-like pool drives the establishment and progression of advanced gastric cancers

Nature cell biology

2021 Dec 01

Fatehullah, A;Terakado, Y;Sagiraju, S;Tan, TL;Sheng, T;Tan, SH;Murakami, K;Swathi, Y;Ang, N;Rajarethinam, R;Ming, T;Tan, P;Lee, B;Barker, N;
PMID: 34857912 | DOI: 10.1038/s41556-021-00793-9

Gastric cancer is among the most prevalent and deadliest of cancers globally. To derive mechanistic insight into the pathways governing this disease, we generated a Claudin18-IRES-CreERT2 allele to selectively drive conditional dysregulation of the Wnt, Receptor Tyrosine Kinase and Trp53 pathways within the gastric epithelium. This resulted in highly reproducible metastatic, chromosomal-instable-type gastric cancer. In parallel, we developed orthotopic cancer organoid transplantation models to evaluate tumour-resident Lgr5+ populations as functional cancer stem cells via in vivo ablation. We show that Cldn18 tumours accurately recapitulate advanced human gastric cancer in terms of disease morphology, aberrant gene expression, molecular markers and sites of distant metastases. Importantly, we establish that tumour-resident Lgr5+ stem-like cells are critical to the initiation and maintenance of tumour burden and are obligatory for the establishment of metastases. These models will be invaluable for deriving clinically relevant mechanistic insights into cancer progression and as preclinical models for evaluating therapeutic targets.

Inhibition of the cGAS-STING pathway ameliorates the premature senescence hallmarks of Ataxia-Telangiectasia brain organoids

Aging cell

2021 Sep 01

Aguado, J;Chaggar, HK;Gómez-Inclán, C;Shaker, MR;Leeson, HC;Mackay-Sim, A;Wolvetang, EJ;
PMID: 34459078 | DOI: 10.1111/acel.13468

Ataxia-telangiectasia (A-T) is a genetic disorder caused by the lack of functional ATM kinase. A-T is characterized by chronic inflammation, neurodegeneration and premature ageing features that are associated with increased genome instability, nuclear shape alterations, micronuclei accumulation, neuronal defects and premature entry into cellular senescence. The causal relationship between the detrimental inflammatory signature and the neurological deficiencies of A-T remains elusive. Here, we utilize human pluripotent stem cell-derived cortical brain organoids to study A-T neuropathology. Mechanistically, we show that the cGAS-STING pathway is required for the recognition of micronuclei and induction of a senescence-associated secretory phenotype (SASP) in A-T olfactory neurosphere-derived cells and brain organoids. We further demonstrate that cGAS and STING inhibition effectively suppresses self-DNA-triggered SASP expression in A-T brain organoids, inhibits astrocyte senescence and neurodegeneration, and ameliorates A-T brain organoid neuropathology. Our study thus reveals that increased cGAS and STING activity is an important contributor to chronic inflammation and premature senescence in the central nervous system of A-T and constitutes a novel therapeutic target for treating neuropathology in A-T patients.

Specific Connectivity and Unique Molecular Identity of MET Receptor Tyrosine Kinase Expressing Serotonergic Neurons in the Caudal Dorsal Raphe Nuclei

ACS Chem Neurosci.

2017 May 01

Kast RJ, Wu HH, Williams P, Gaspar P, Levitt P.
PMID: 28375615 | DOI: 10.1021/acschemneuro.7b00020

Molecular characterization of neurons across brain regions has revealed new taxonomies for understanding functional diversity even among classically defined neuronal populations. Neuronal diversity has become evident within the brain serotonin (5-HT) system, which is far more complex than previously appreciated. However, until now it has been difficult to define subpopulations of 5-HT neurons based on molecular phenotypes. We demonstrate that the MET receptor tyrosine kinase (MET) is specifically expressed in a subset of 5-HT neurons within the caudal part of the dorsal raphe nuclei (DRC) that is encompassed by the classic B6 serotonin cell group. Mapping from embryonic day 16 through adulthood reveals that MET is expressed almost exclusively in the DRC as a condensed, paired nucleus, with an additional sparse set of MET+ neurons scattered within the median raphe. Retrograde tracing experiments reveal that MET-expressing 5-HT neurons provide substantial serotonergic input to the ventricular/subventricular region that contains forebrain stem cells, but do not innervate the dorsal hippocampus or entorhinal cortex. Conditional anterograde tracing experiments show that 5-HT neurons in the DRC/B6 target additional forebrain structures such as the medial and lateral septum and the ventral hippocampus. Molecular neuroanatomical analysis identifies 14 genes that are enriched in DRC neurons, including 4 neurotransmitter/neuropeptide receptors and 2 potassium channels. These analyses will lead to future studies determining the specific roles that 5-HTMET+ neurons contribute to the broader set of functions regulated by the serotonergic system.

Massive Multiplexing of Spatially Resolved Single Neuron Projections with Axonal BARseq

bioRxiv : the preprint server for biology

2023 Feb 18

Yuan, L;Chen, X;Zhan, H;Gilbert, HL;Zador, AM;
PMID: 36824753 | DOI: 10.1101/2023.02.18.528865

Neurons in the cortex are heterogenous, sending diverse axonal projections to multiple brain regions. Unraveling the logic of these projections requires single-neuron resolution. Although a growing number of techniques have enabled high-throughput reconstruction, these techniques are typically limited to dozens or at most hundreds of neurons per brain, requiring that statistical analyses combine data from different specimens. Here we present axonal BARseq, a high-throughput approach based on reading out nucleic acid barcodes using in situ RNA sequencing, which enables analysis of even densely labeled neurons. As a proof of principle, we have mapped the long-range projections of >8000 mouse primary auditory cortex neurons from a single brain. We identified major cell types based on projection targets and axonal trajectory. The large sample size enabled us to systematically quantify the projections of intratelencephalic (IT) neurons, and revealed that individual IT neurons project to different layers in an area-dependent fashion. Axonal BARseq is a powerful technique for studying the heterogeneity of single neuronal projections at high throughput within individual brains.

Independent response modulation of visual cortical neurons by attentional and behavioral states

Neuron

2022 Sep 16

Kanamori, T;Mrsic-Flogel, TD;
PMID: 36137550 | DOI: 10.1016/j.neuron.2022.08.028

Sensory processing is influenced by cognitive and behavioral states, but how these states interact to modulate responses of individual neurons is unknown. We trained mice in a visual discrimination task wherein they attended to different locations within a hemifield while running or sitting still, enabling us to examine how visual responses are modulated by spatial attention and running behavior. We found that spatial attention improved discrimination performance and strengthened visual responses of excitatory neurons in the primary visual cortex whose receptive fields overlapped with the attended location. Although individual neurons were modulated by both spatial attention and running, the magnitudes of these influences were not correlated. While running-dependent modulation was stable across days, attentional modulation was dynamic, influencing individual neurons to different degrees after repeated changes in attentional states. Thus, despite similar effects on neural responses, spatial attention and running act independently with different dynamics, implying separable mechanisms for their implementation.

Early Pathogenesis in Rabbit Hemorrhagic Disease Virus 2

SSRN Electronic Journal

2022 Sep 10

O'Toole, A;Mohamed, F;Zhang, J;Brown, C;
| DOI: 10.2139/ssrn.4199232

To detail early tissue distribution and innate immune response to rabbit hemorrhagic disease virus 2 (RHDV2), 13 rabbits were orally ( Oryctolagus cuniculus ) inoculated with liver homogenate made from a feral rabbit that succumbed to RHDV2 during the 2020 outbreak in Oregon, USA. Rabbits were monitored regularly, with euthanasia and collection of tissues and swabs, at 12, 24, 36, 48, 96, and 144 hours post inoculation. Livers from these rabbits were positive by RT-rtPCR for presence of the virus. Using RNAscope for viral and replicative intermediates, rabbits had detectable viral genomic RNA at each time point, initially within the gastrointestinal tract, then in the liver by 36 hours post inoculation. Also using RNAscope, there were increasing amounts of mRNA coding for TNF-α, IL-6, and IL-1β within the liver and spleen through 48 hours post inoculation. The results of this study aided our understanding of the local innate immune response to RHDV2, as well as aspects of pathogenesis.

Regulation of energy rheostasis by the melanocortin-3 receptor

Sci Adv.

2018 Aug 22

Ghamari-Langroudi M, Cakir I, Lippert RN, Sweeney P, Litt MJ, Ellacott KLJ, Cone RD.
PMID: 30140740 | DOI: 10.1126/sciadv.aat0866

Like most homeostatic systems, adiposity in mammals is defended between upper and lower boundary conditions. While leptin and melanocortin-4 receptor (MC4R) signaling are required for defending energy set point, mechanisms controlling upper and lower homeostatic boundaries are less well understood. In contrast to the MC4R, deletion of the MC3R does not produce measurable hyperphagia or hypometabolism under normal conditions. However, we demonstrate that MC3R is required bidirectionally for controlling responses to external homeostatic challenges, such as caloric restriction or calorie-rich diet. MC3R is also required for regulated excursion from set point, or rheostasis, during pregnancy. Further, we demonstrate a molecular mechanism: MC3R provides regulatory inputs to melanocortin signaling, acting presynaptically on agouti-related protein neurons to regulate γ-aminobutyric acid release onto anorexigenic MC4R neurons, exerting boundary control on the activity of MC4R neurons. Thus, the MC3R is a critical regulator of boundary controls on melanocortin signaling, providing rheostatic control on energy storage.

Severe COVID-19 infection is associated with aberrant cytokine production by infected lung epithelial cells rather than by systemic immune dysfunction

Research square

2021 Nov 24

Gajewski, T;Rouhani, S;Trujillo, J;Pyzer, A;Yu, J;Fessler, J;Cabanov, A;Higgs, E;Cron, K;Zha, Y;Lu, Y;Bloodworth, J;Abasiyanik, M;Okrah, S;Flood, B;Hatogai, K;Leung, M;Pezeshk, A;Kozloff, L;Reschke, R;Strohbehn, G;Chervin, CS;Kumar, M;Schrantz, S;Madariaga, ML;Beavis, K;Yeo, KT;Sweis, R;Segal, J;Tay, S;Izumchenko, E;Mueller, J;Chen, L;
PMID: 34845442 | DOI: 10.21203/rs.3.rs-1083825/v1

The mechanisms explaining progression to severe COVID-19 remain poorly understood. It has been proposed that immune system dysregulation/over-stimulation may be implicated, but it is not clear how such processes would lead to respiratory failure. We performed comprehensive multiparameter immune monitoring in a tightly controlled cohort of 128 COVID-19 patients, and used the ratio of oxygen saturation to fraction of inspired oxygen (SpO2 / FiO2) as a physiologic measure of disease severity. Machine learning algorithms integrating 139 parameters identified IL-6 and CCL2 as two factors predictive of severe disease, consistent with the therapeutic benefit observed with anti-IL6-R antibody treatment. However, transcripts encoding these cytokines were not detected among circulating immune cells. Rather, in situ analysis of lung specimens using RNAscope and immunofluorescent staining revealed that elevated IL-6 and CCL2 were dominantly produced by infected lung type II pneumocytes. Severe disease was not associated with higher viral load, deficient antibody responses, or dysfunctional T cell responses. These results refine our understanding of severe COVID-19 pathophysiology, indicating that aberrant cytokine production by infected lung epithelial cells is a major driver of immunopathology. We propose that these factors cause local immune regulation towards the benefit of the virus.

Mast cells in lung damage of COVID-19 autopsies: A descriptive study

Allergy

2022 Mar 27

Schaller, T;Märkl, B;Claus, R;Sholl, L;Hornick, JL;Giannetti, MP;Schweizer, L;Mann, M;Castells, M;
PMID: 35340030 | DOI: 10.1111/all.15293

Innate Immune Pathways Promote Oligodendrocyte Progenitor Cell Recruitment to the Injury Site in Adult Zebrafish Brain

Cells

2022 Feb 02

Sanchez-Gonzalez, R;Koupourtidou, C;Lepko, T;Zambusi, A;Novoselc, KT;Durovic, T;Aschenbroich, S;Schwarz, V;Breunig, CT;Straka, H;Huttner, HB;Irmler, M;Beckers, J;Wurst, W;Zwergal, A;Schauer, T;Straub, T;Czopka, T;Trümbach, D;Götz, M;Stricker, SH;Ninkovic, J;
PMID: 35159329 | DOI: 10.3390/cells11030520

The oligodendrocyte progenitors (OPCs) are at the front of the glial reaction to the traumatic brain injury. However, regulatory pathways steering the OPC reaction as well as the role of reactive OPCs remain largely unknown. Here, we compared a long-lasting, exacerbated reaction of OPCs to the adult zebrafish brain injury with a timely restricted OPC activation to identify the specific molecular mechanisms regulating OPC reactivity and their contribution to regeneration. We demonstrated that the influx of the cerebrospinal fluid into the brain parenchyma after injury simultaneously activates the toll-like receptor 2 (Tlr2) and the chemokine receptor 3 (Cxcr3) innate immunity pathways, leading to increased OPC proliferation and thereby exacerbated glial reactivity. These pathways were critical for long-lasting OPC accumulation even after the ablation of microglia and infiltrating monocytes. Importantly, interference with the Tlr1/2 and Cxcr3 pathways after injury alleviated reactive gliosis, increased new neuron recruitment, and improved tissue restoration.

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	Description
sense Example: Hs-LAG3-sense	Standard probes for RNA detection are in antisense. Sense probe is reverse complent to the corresponding antisense probe.
Intron# Example: Mm-Htt-intron2	Probe targets the indicated intron in the target gene, commonly used for pre-mRNA detection
Pool/Pan Example: Hs-CD3-pool (Hs-CD3D, Hs-CD3E, Hs-CD3G)	A mixture of multiple probe sets targeting multiple genes or transcripts
No-XSp Example: Hs-PDGFB-No-XMm	Does not cross detect with the species (Sp)
XSp Example: Rn-Pde9a-XMm	designed to cross detect with the species (Sp)
O# Example: Mm-Islr-O1	Alternative design targeting different regions of the same transcript or isoforms
CDS Example: Hs-SLC31A-CDS	Probe targets the protein-coding sequence only
EnEm	Probe targets exons n and m
En-Em	Probe targets region from exon n to exon m
Retired Nomenclature
tvn Example: Hs-LEPR-tv1	Designed to target transcript variant n
ORF Example: Hs-ACVRL1-ORF	Probe targets open reading frame
UTR Example: Hs-HTT-UTR-C3	Probe targets the untranslated region (non-protein-coding region) only
5UTR Example: Hs-GNRHR-5UTR	Probe targets the 5' untranslated region only
3UTR Example: Rn-Npy1r-3UTR	Probe targets the 3' untranslated region only
Pan Example: Pool	A mixture of multiple probe sets targeting multiple genes or transcripts

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