Cited by 225Neuroinflammation and Neurodegeneration MechanismsRedox biology and oxidative stressNeutrophil, Myeloperoxidase and Oxidative Mechanisms

The DOI matches its Crossref record; 75 of the 75 references it cites were found in a registry or an index; 24 of the 66 sources its claims cite were checked for support.

Neurotoxic Activation of Microglia Is Promoted by a Nox1-Dependent NADPH Oxidase

Open access

Abstract

Reactive oxygen species (ROS) modulate intracellular signaling but are also responsible for neuronal damage in pathological states. Microglia, the resident CNS macrophages, are prominent sources of ROS through expression of the phagocyte oxidase which catalytic subunit Nox2 generates superoxide ion (O 2 ·− ). Here we show that microglia also express Nox1 and other components of nonphagocyte NADPH oxidases, including p22 phox , NOXO1, NOXA1, and Rac1/2. The subcellular distribution and functions of Nox1 were determined by blocking Nox activity with diphenylene iodonium or apocynin, and by silencing the Nox1 gene in microglia purified from wild-type (WT) or Nox2-KO mice. [Nox1-p22 phox ] dimers localized in intracellular compartments are recruited to phagosome membranes during microglial phagocytosis of zymosan, and Nox1 produces O 2 ·− in zymosan-loaded phagosomes. In microglia activated with lipopolysaccharide (LPS), Nox1 produces O 2 ·− , which enhances cell expression of inducible nitric oxide synthase and secretion of interleukin-1β. Comparisons of microglia purified from WT, Nox2-KO, or Nox1-KO mice indicate that both Nox1 and Nox2 are required to optimize microglial production of nitric oxide. By injecting LPS in the striatum of WT and Nox1-KO mice, we show that Nox1 also enhances microglial production of cytotoxic nitrite species and promotes loss of presynaptic proteins in striatal neurons. These results demonstrate the functional expression of Nox1 in resident CNS phagocytes, which can promote production of neurotoxic compounds during neuroinflammation. Our study also shows that Nox1- and Nox2-dependent oxidases play distinct roles in microglial activation and that Nox1 is a possible target for the treatment of neuroinflammatory states.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

Microglia express a Nox1-dependent NADPH oxidase in addition to the phagocyte Nox2 oxidase, and Nox1 generates intracellular/phagosomal superoxide that promotes LPS-induced IL-1β, nitric oxide, and peroxynitrite-related neurotoxicity. In vivo, Nox1 deletion reduced tyrosine nitration in activated microglia and prevented LPS-induced loss of striatal synapsin.

Key findings

  • Microglia express Nox1 and the nonphagocyte NADPH oxidase components p22phox, NOXO1, NOXA1, and Rac1/2, while Nox3, Nox4, Duox1, and Duox2 transcripts were not detectable.
  • [Nox1-p22phox] dimers localize to intracellular compartments, including lysosomes, and are recruited to phagosome membranes during zymosan phagocytosis; zymosan increased hydroethidine oxidation 15-fold in WT microglia but only 5-fold in Nox2-KO microglia, and DPI abolished this signal.
  • LPS activated both Nox1 and Nox2; Nox1 promoted IL-1β and NO production. DPI reduced IL-1β secretion by 65%, apocynin reduced it by >60%, and shNox1 reduced IL-1β by at least 45%; Nox2-KO microglia produced 50% less NO than WT, Nox1 silencing reduced NO by at least 50%, and Nox1-KO microglia produced 23–73% less nitrite than WT.
  • After intrastriatal LPS, the proportion of Ntyr-stained microglia fell from 91 ± 9% in WT to 47 ± 16% in Nox1-KO mice, and WT mice showed a 40% decrease in synapsin immunoreactivity while Nox1-KO mice showed no synapsin loss.

Methods

  • Microglia were purified by FACS from CX3CR1-EGFP mice or prepared from primary cultures of WT, Nox2-KO, and Nox1-KO mice; expression was assessed by RT-PCR, quantitative real-time PCR, Western blot, and immunocytochemistry.
  • Nox1 was silenced with siRNA or lentiviral shRNA; Nox activity was blocked with DPI or apocynin; superoxide was detected by hydroethidine oxidation and NBT reduction, IL-1β by ELISA, and NO by nitrite/Griess measurement.
  • In vivo, LPS was injected unilaterally into the striatum of 21-week-old male WT and Nox1-KO littermates, and brains were analyzed 4 days later by immunohistofluorescence for microglia, astrocytes, synapsin, and nitrotyrosine.

Limitations

  • The paper states that antibodies selectively reacting with murine Nox1 were unavailable, so p22phox distribution was used to infer Nox1 localization; DPI can also inhibit other flavoenzymes; and it cannot be ruled out that Nox1 protein levels or Nox1-derived O2− differ between WT and Nox2-KO microglia.
  • The paper states that the precise mechanism of the synaptic alteration remains to be determined.
  • Evident from the text: double Nox1/Nox2 knockout mice were not used because both genes are on chromosome X, so the study relied on pharmacological inhibition and shNox1 silencing in Nox2-KO cells; in vivo analysis was limited to LPS-injected striatum at 4 days, and TUNEL staining detected very few degenerating cells.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1523/jneurosci.3568-08.2008

Cites

75 of 75 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Figures

Figure 1 Microglia express the genes encoding Nox1- and Nox2-dependent NADPH oxidases. Ethidium bromide-stained agarose gels of reverse transcription-PCR products generated fromNox1,p22 phox , NOXO1, NOXA1, Rac1, Rac2, Nox2, p40 phox , p47 phox , and p67 phox mRNAin microglia purified by FACS from CX3CR1 EGFP/ + mice or from Nox3, Nox4, Duox1, or Duox2 mRNA in FACS-purified CX3CR1 EGFP/ + microglia (M), inner ear from P3 mice (IE), kidney from 16-d-old mice embryos (Kd), or adult mouse thyroid (Th). IE, Kd, and Th were from WT mice and were used as positive controls.
Figure 1 Microglia express the genes encoding Nox1- and Nox2-dependent NADPH oxidases. Ethidium bromide-stained agarose gels of reverse transcription-PCR products generated fromNox1,p22 phox , NOXO1, NOXA1, Rac1, Rac2, Nox2, p40 phox , p47 phox , and p67 phox mRNAin microglia purified by FACS from CX3CR1 EGFP/ + mice or from Nox3, Nox4, Duox1, or Duox2 mRNA in FACS-purified CX3CR1 EGFP/ + microglia (M), inner ear from P3 mice (IE), kidney from 16-d-old mice embryos (Kd), or adult mouse thyroid (Th). IE, Kd, and Th were from WT mice and were used as positive controls.CC-BY-NC-SA · From the PDF
Figure 2 Nox1- and Nox2-dependent localization of p22 phox in microglia. A , Codetection of p22 phox (anti-p22 phox , green), lysosomes (anti-LAMP1, red), and nuclei (Hoechst 33342, blue) in cultured WT or Nox2-KO microglia. Plasma membranes are outlined by open arrowheads. White arrowheads point to lysosomal p22 phox in merged views (confocal microscopy). Scale bars, 10 𝛍 m. B , Detection of p22 phox (green) and nucleic acid (Hoechst staining, blue fluorescence converted to red) in a Nox2-KO murine microglial cell after microglial phagocytosis of yeast particles (zymosan). The plasma membrane is outlined in yellow. Culturedcells wereincubatedwithzymosanfor45minbeforefixationandstaining.Notethelocalizationofp22 phox in phagosome membranessurroundingstainednucleicacidofyeastparticles(confocalmicroscopy). Scale bar, 10 𝛍 m. C , Suppression of p22 phox expression in Nox2-KO microglial cells transduced with shNox1. Cultures of purified Nox2-KO microglia were transduced with lentiviral shNox1 or shCtrl and cultured for 3 d before fixation and codetection of p22 phox (anti-p22 phox , red) and EGFP (anti-EGFP, green). Cells transduced with lentiviral shRNA express EGFP. Scale bar, 20 𝛍 m.
Figure 2 Nox1- and Nox2-dependent localization of p22 phox in microglia. A , Codetection of p22 phox (anti-p22 phox , green), lysosomes (anti-LAMP1, red), and nuclei (Hoechst 33342, blue) in cultured WT or Nox2-KO microglia. Plasma membranes are outlined by open arrowheads. White arrowheads point to lysosomal p22 phox in merged views (confocal microscopy). Scale bars, 10 𝛍 m. B , Detection of p22 phox (green) and nucleic acid (Hoechst staining, blue fluorescence converted to red) in a Nox2-KO murine microglial cell after microglial phagocytosis of yeast particles (zymosan). The plasma membrane is outlined in yellow. Culturedcells wereincubatedwithzymosanfor45minbeforefixationandstaining.Notethelocalizationofp22 phox in phagosome membranessurroundingstainednucleicacidofyeastparticles(confocalmicroscopy). Scale bar, 10 𝛍 m. C , Suppression of p22 phox expression in Nox2-KO microglial cells transduced with shNox1. Cultures of purified Nox2-KO microglia were transduced with lentiviral shNox1 or shCtrl and cultured for 3 d before fixation and codetection of p22 phox (anti-p22 phox , red) and EGFP (anti-EGFP, green). Cells transduced with lentiviral shRNA express EGFP. Scale bar, 20 𝛍 m.CC-BY-NC-SA · From the PDF
Figure 3 Detection of phagosomal O 2 H18528 -in Nox2-KO microglia engulfing zymosan. A , Cultured Nox2-KO microglia were incubated for 30 min with zymosan (Zym) in the absence or the presence of DPI, before addition of NBT to the culture for 15 min. TL, Transmittedlight. DIC, Differential interference contrast. White and black arrowheads indicate extracellular and engulfed yeast particles, respectively. The dark blue formazan deposit overlying the phagosomal membrane is not observed in DPI-treated cells. B , Red fluorescence emitted by oxidized hydroethidine (Ox-HE) in a Nox2-KO microglial cell (same cell as in Fig. 2 B ) after a 45 min incubation with zymosan in the presence of cell-permeant hydroethidine. The DNA of the cell and engulfed zymosan were counterstained with Hoechst 33342 (blue fluorescence converted to green), and the cell nucleus and the plasma membrane are outlined in yellow and white, respectively. Ox-HE fluorescence is colocalized with the DNA of engulfed zymosan (confocal microscopy). Scale bars, 10 𝛍 m.
Figure 3 Detection of phagosomal O 2 H18528 -in Nox2-KO microglia engulfing zymosan. A , Cultured Nox2-KO microglia were incubated for 30 min with zymosan (Zym) in the absence or the presence of DPI, before addition of NBT to the culture for 15 min. TL, Transmittedlight. DIC, Differential interference contrast. White and black arrowheads indicate extracellular and engulfed yeast particles, respectively. The dark blue formazan deposit overlying the phagosomal membrane is not observed in DPI-treated cells. B , Red fluorescence emitted by oxidized hydroethidine (Ox-HE) in a Nox2-KO microglial cell (same cell as in Fig. 2 B ) after a 45 min incubation with zymosan in the presence of cell-permeant hydroethidine. The DNA of the cell and engulfed zymosan were counterstained with Hoechst 33342 (blue fluorescence converted to green), and the cell nucleus and the plasma membrane are outlined in yellow and white, respectively. Ox-HE fluorescence is colocalized with the DNA of engulfed zymosan (confocal microscopy). Scale bars, 10 𝛍 m.CC-BY-NC-SA · From the PDF
Figure 4 Contributions of Nox1 and Nox2 to intracellular O 2 H18528 -levels in activated microglia. A , B , Cultured WT and Nox2-KO microglia were incubated for 45 min with cell-permeant hydroethidine in the absence (Ctrl) or the presence of LPS or zymosan and with or without DPI before assessment of hydroethidine oxidation. A , Red fluorescence resulting of hydroethidine oxidation in cells that have ingested zymosan. Strongly enhanced fluorescence is localized in phagosomes containing zymosan in WT or Nox2-KO cells. Fluorescence is strongly reduced when cells are incubated with DPI. Hoechst 33342 dye counterstaining (blue) reveals cell nuclei. Scale bar, 10 𝛍 m. B , Levels of oxidized hydroethidine (Ox-HE) were determined by fluorescence intensity normalized to the number of cells and are expressed as the percentage of the mean control value determined in cultures without LPS, zymosan or DPI. In zymosan-treated cultures, Ox-HE levels were determined in cells containing at least 10 zymosan particles. Data are the mean ± SDoftwo(Nox2-KOcells) or three (WT cells) separate experiments with 5-15 determinations in sister wells
Figure 4 Contributions of Nox1 and Nox2 to intracellular O 2 H18528 -levels in activated microglia. A , B , Cultured WT and Nox2-KO microglia were incubated for 45 min with cell-permeant hydroethidine in the absence (Ctrl) or the presence of LPS or zymosan and with or without DPI before assessment of hydroethidine oxidation. A , Red fluorescence resulting of hydroethidine oxidation in cells that have ingested zymosan. Strongly enhanced fluorescence is localized in phagosomes containing zymosan in WT or Nox2-KO cells. Fluorescence is strongly reduced when cells are incubated with DPI. Hoechst 33342 dye counterstaining (blue) reveals cell nuclei. Scale bar, 10 𝛍 m. B , Levels of oxidized hydroethidine (Ox-HE) were determined by fluorescence intensity normalized to the number of cells and are expressed as the percentage of the mean control value determined in cultures without LPS, zymosan or DPI. In zymosan-treated cultures, Ox-HE levels were determined in cells containing at least 10 zymosan particles. Data are the mean ± SDoftwo(Nox2-KOcells) or three (WT cells) separate experiments with 5-15 determinations in sister wellsCC-BY-NC-SA · From the PDF
Figure 5 Nox1 promotes microglial production of IL-1 𝛃 . A , B , ELISA determination of IL-1 𝛃 levels in the medium of WT or Nox2-KO microglial cultures treated or not with indicated reagents for 16 h. A , Dots represent mean values in eight WT and eight Nox2-KO independent experiments (5- 6 determinations in sister wells per experiment). Bold lines indicate the mean value calculated from the means of the independent experiments. B , Apocynin (Apo) was used. For each genotype, data are mean ± SD of six determinations in sister wells from a representative experiment (* p < 0.001, SNK test). C , Real-time PCR determination of IL-1 𝛃 mRNA levels in cultures treated for 150 min. IL-1 𝛃 levels are expressed as percentage of the mean value determined in LPS-treated cultures. Data are the mean ± SD of three independent experiments with two determinations in sister wells per experiment (* p < 0.001). D , Microglial cultures transduced with lentiviral shNox1 or shCtrl were treated with LPS for 16 h before ELISA detection of IL-1 𝛃 . For each genotype, data are mean ± SD of six determinations in sister wells from a representative experiment (* p < 0.001, Student's t test). Mean percentage of transduced microglia exceeds 85% for each genotype (WT or Nox2-KO).
Figure 5 Nox1 promotes microglial production of IL-1 𝛃 . A , B , ELISA determination of IL-1 𝛃 levels in the medium of WT or Nox2-KO microglial cultures treated or not with indicated reagents for 16 h. A , Dots represent mean values in eight WT and eight Nox2-KO independent experiments (5- 6 determinations in sister wells per experiment). Bold lines indicate the mean value calculated from the means of the independent experiments. B , Apocynin (Apo) was used. For each genotype, data are mean ± SD of six determinations in sister wells from a representative experiment (* p < 0.001, SNK test). C , Real-time PCR determination of IL-1 𝛃 mRNA levels in cultures treated for 150 min. IL-1 𝛃 levels are expressed as percentage of the mean value determined in LPS-treated cultures. Data are the mean ± SD of three independent experiments with two determinations in sister wells per experiment (* p < 0.001). D , Microglial cultures transduced with lentiviral shNox1 or shCtrl were treated with LPS for 16 h before ELISA detection of IL-1 𝛃 . For each genotype, data are mean ± SD of six determinations in sister wells from a representative experiment (* p < 0.001, Student's t test). Mean percentage of transduced microglia exceeds 85% for each genotype (WT or Nox2-KO).CC-BY-NC-SA · From the PDF
Figure 6 Both Nox1 and Nox2 promote microglial production of NO H18528 . A , B , Cell production of NO H18528 was determined by colorimetric measurement of nitrite levels in the medium of WT or Nox2-KO microglial cultures treated or not with LPS or LPS and apocynin for 16 h. A , Dots represent mean values in 15 WT and 13 Nox2-KO independent experiments (5- 6 determinations in sister wells per experiment). Bold lines indicate the mean value calculated from the means of the independent experiments. B , For each genotype, data are mean ± SDofsix determinations in sister wells from a representative experiment (* p < 0.01, SNK test). C , D , Real-time PCR determination of iNOS mRNA levels and Western blot detection of INOS protein in WT ( C ) or Nox2-KO ( D )
Figure 6 Both Nox1 and Nox2 promote microglial production of NO H18528 . A , B , Cell production of NO H18528 was determined by colorimetric measurement of nitrite levels in the medium of WT or Nox2-KO microglial cultures treated or not with LPS or LPS and apocynin for 16 h. A , Dots represent mean values in 15 WT and 13 Nox2-KO independent experiments (5- 6 determinations in sister wells per experiment). Bold lines indicate the mean value calculated from the means of the independent experiments. B , For each genotype, data are mean ± SDofsix determinations in sister wells from a representative experiment (* p < 0.01, SNK test). C , D , Real-time PCR determination of iNOS mRNA levels and Western blot detection of INOS protein in WT ( C ) or Nox2-KO ( D )CC-BY-NC-SA · From the PDF
Figure 7 Nox1 gene deletion reduces the level of tyrosine nitration without affecting recruitment of activated microglia in LPS-injected brain. Brains were fixed 4 d after intrastriatal injection of LPS. Top, Striatal sections in the vicinity of the injection site from WT and Nox1-KO mice double stained with rabbit polyclonal anti-Ntyr (green) and a combination of rat monoclonal anti-F4/80, anti-CD-68, and anti-CD11b antibodies that bind to microglial cells (Microglia, red). Scale bar, 100 𝛍 m. Bottom, High-powerview(apotome)ofamicroglialcellbodystainedwithanti-Ntyr.Hoechststainingofthenucleus(blue)isshowninthe merge view. Scale bar, 10 𝛍 m.
Figure 7 Nox1 gene deletion reduces the level of tyrosine nitration without affecting recruitment of activated microglia in LPS-injected brain. Brains were fixed 4 d after intrastriatal injection of LPS. Top, Striatal sections in the vicinity of the injection site from WT and Nox1-KO mice double stained with rabbit polyclonal anti-Ntyr (green) and a combination of rat monoclonal anti-F4/80, anti-CD-68, and anti-CD11b antibodies that bind to microglial cells (Microglia, red). Scale bar, 100 𝛍 m. Bottom, High-powerview(apotome)ofamicroglialcellbodystainedwithanti-Ntyr.Hoechststainingofthenucleus(blue)isshowninthe merge view. Scale bar, 10 𝛍 m.CC-BY-NC-SA · From the PDF
Figure 8 Nox1 deletion prevents loss of synapsin in LPS-injected mouse striatum. A-C , Striatal fields from WT and Nox1-KO mice stained with rabbit polyclonal anti-Iba1 (microglial staining) ( A ), anti-GFAP (astrocyte staining) ( B ), or anti-synapsin ( C ) ipsilateral or contralateral to the lesional tract and localized 300 𝛍 m ventral to the injection site. Scale bars, 50 𝛍 m. D , Data represent the area of synapsin staining in ipsilateral striata normalized to the contralateral region for each genotype (mean ± SD from 5 animals of each genotype, * p < 0.01, Student's t test).
Figure 8 Nox1 deletion prevents loss of synapsin in LPS-injected mouse striatum. A-C , Striatal fields from WT and Nox1-KO mice stained with rabbit polyclonal anti-Iba1 (microglial staining) ( A ), anti-GFAP (astrocyte staining) ( B ), or anti-synapsin ( C ) ipsilateral or contralateral to the lesional tract and localized 300 𝛍 m ventral to the injection site. Scale bars, 50 𝛍 m. D , Data represent the area of synapsin staining in ipsilateral striata normalized to the contralateral region for each genotype (mean ± SD from 5 animals of each genotype, * p < 0.01, Student's t test).CC-BY-NC-SA · From the PDF

Verification

Claims the paper makes

75 Own result · 31 Own interpretation · 16 No full text of the sources · 10 Partly supported · 8 Own method · 7 Supported · 5 No basis given · 4 Sources not found · 3 Not checked yet · 2 Supported so far · accuracy not yet measured

Show all 97 claims

  • Probably not a substantial claim. 37
  • It may state two separate claims as one. 34
  • The quote only partly states this claim. 1
64 of 64
  • The paper relies on this without support.

    LPS injection into the mouse striatum produces a neuroinflammatory lesion that models the neural tissue damage occurring in human neurodegenerative or inflammatory diseases.

    “causes synaptic damage in a LPS-triggered neuroinflammatory lesion.”
  • The paper relies on this without support.

    Nox1-KO mice lack Nox1 function.

    “we injected LPS unilaterally into the striatum of adult WT or Nox1-KO mice from the same litter”
  • The paper relies on this without support.

    The anti-Ntyr antibody specifically detects tyrosine nitration.

    “the proportion of microglial cells stained with anti-Ntyr”
  • The paper relies on this without support.

    Decreased synapsin immunoreactivity reflects loss of synaptic proteins or synaptic damage.

    “Synapsin immunoreactivity was decreased”
  • The paper relies on this without support.

    The density of microglial cells counted in the cortical area reflects the overall microglial recruitment or activation.

    “The density of microglial cells determined by counts in microscopic fields”
5 of 5

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

2 of 2

Citations

Cites

Show all 74 references

Cited by

Sorted by citations

Metadata

Authors
Chéret, C., Gervais, A., Lelli, A., Colin, C., Amar, L., Ravassard, P., Mallet, J., Cumano, A., Krause, K.-H., & Mallat, M.
Affiliations
  • Inserm (FR)
  • Centre National de la Recherche Scientifique (FR)
  • University of Geneva (CH)
Venue
The Journal of Neuroscience
Published
2008-11-12
Volume
28
Issue
46
Pages
12039-12051
ISSN
  • 0270-6474 (ISSN-L)
  • 1529-2401
OpenAlex
W2091043188
Cited by
225
References
74
Citations by year
2026: 4 · 2025: 9 · 2024: 10 · 2023: 9 · 2022: 9 · 2021: 10 · 2020: 10 · 2019: 6 · 2018: 15 · 2017: 17 · 2016: 20 · 2015: 11 · 2014: 20 · 2013: 18 · 2012: 19
FWCI
8.31
Type
journal article
Language
en
Open access
Locations
  • Journal of Neuroscience (publishedVersion, cc-by-nc-sa)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Archive ouverte UNIGE (University of Geneva) (acceptedVersion)
  • HAL (submittedVersion, other-oa)
  • Archive ouverte UNIGE (University of Geneva) (submittedVersion, cc-by)
Funders
Institut National de la Santé et de la Recherche Médicale
Topics
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
  • Life Sciences › Immunology and Microbiology › Immunology › Neutrophil, Myeloperoxidase and Oxidative Mechanisms
Keywords
NOX1, NADPH oxidase, microglia, reactive oxygen species, superoxide, NOX2, neuroinflammation, microglial activation, nitric oxide, inducible nitric oxide synthase, IL-1β, phagosome, lipopolysaccharide, zymosan, striatum, neurotoxicity, presynaptic proteins, diphenyleneiodonium, apocynin
MeSH terms
NADPH Oxidase 1, NADPH Oxidase 2, Animals, Corpus Striatum, Cytochrome b Group, Encephalitis, Female, Gliosis, Lipopolysaccharides, Male, Membrane Glycoproteins, Mice, Inbred C57BL, NADH, NADPH Oxidoreductases, Neuropeptides, Neurotoxins, Nitrites, Proteins, Zymosan, Reactive Oxygen Species, Microglia, Mice, Knockout, Oxidative Stress, Inflammation Mediators, NADPH Oxidases, rac GTP-Binding Proteins, rac1 GTP-Binding Protein, Adaptor Proteins, Signal Transducing, Mice

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-11-02, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-11-02 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Cited sources are checked with a language model’s help (gpt-6-sol).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review