Cited by 1,455Cytokine Signaling Pathways and InteractionsNF-κB Signaling PathwaysRheumatoid Arthritis Research and Therapies

The DOI matches its Crossref record; 382 of the 390 references it cites were found in a registry or an index; 220 of the 329 sources its claims cite were checked for support.

IL-6 in inflammation, autoimmunity and cancer

Open access
Hirano, Toshio·2021·International Immunology

Abstract

IL-6 is involved both in immune responses and in inflammation, hematopoiesis, bone metabolism and embryonic development. IL-6 plays roles in chronic inflammation (closely related to chronic inflammatory diseases, autoimmune diseases and cancer) and even in the cytokine storm of corona virus disease 2019 (COVID-19). Acute inflammation during the immune response and wound healing is a well-controlled response, whereas chronic inflammation and the cytokine storm are uncontrolled inflammatory responses. Non-immune and immune cells, cytokines such as IL-1β, IL-6 and tumor necrosis factor alpha (TNFα) and transcription factors nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) play central roles in inflammation. Synergistic interactions between NF-κB and STAT3 induce the hyper-activation of NF-κB followed by the production of various inflammatory cytokines. Because IL-6 is an NF-κB target, simultaneous activation of NF-κB and STAT3 in non-immune cells triggers a positive feedback loop of NF-κB activation by the IL-6–STAT3 axis. This positive feedback loop is called the IL-6 amplifier (IL-6 Amp) and is a key player in the local initiation model, which states that local initiators, such as senescence, obesity, stressors, infection, injury and smoking, trigger diseases by promoting interactions between non-immune cells and immune cells. This model counters dogma that holds that autoimmunity and oncogenesis are triggered by the breakdown of tissue-specific immune tolerance and oncogenic mutations, respectively. The IL-6 Amp is activated by a variety of local initiators, demonstrating that the IL-6–STAT3 axis is a critical target for treating diseases.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

IL-6 is a pleiotropic cytokine discovered in 1986 that acts through IL-6–STAT3 signaling and the IL-6 amplifier (IL-6 Amp), a STAT3/NF-κB-driven amplification loop, to link inflammation, autoimmunity and cancer. The review proposes a local initiation model in which infection, injury, stress, senescence, obesity and oncogenic mutations activate the IL-6 Amp in non-immune cells, recruiting immune cells and driving chronic disease.

Key findings

  • IL-6 is a prototypical member of the 10-member IL-6 family and signals via classic, trans-signaling and trans-presentation modes; trans-signaling expands IL-6 targets to cells expressing only gp130, including fibroblasts and endothelial cells.
  • IL-6–STAT3 signaling regulates Th17/Treg balance, plasma cell differentiation, dendritic cell maturation, M2 macrophages, MDSCs and PD-L1 expression, and promotes cancer cell survival, proliferation, EMT, angiogenesis and metastasis.
  • The IL-6 Amp synergistically amplifies IL-6 and other pro-inflammatory mediators through STAT3 and NF-κB; a comparative analysis found 202 of 1700 screened genes showed over 490 indications of association with autoimmune, metabolic, neurodegenerative and other chronic inflammatory diseases.
  • IL-6 correlates with prognosis across 23 cancer types; in mouse models, F759 mice spontaneously develop IL-6-dependent, CD4+ T-cell-dependent arthritis, while gp130Y757F/Y757F mice show gastric hyperproliferative lesions as early as 6 weeks.

Methods

  • Narrative review synthesizing mechanistic, genetic, mouse-model and clinical literature on IL-6 in inflammation, autoimmunity and cancer.
  • Discusses mouse models including F759, gp130Y757F/Y757F, IL-6 transgenic and IL-6-deficient mice, plus GWAS/SNP associations and clinical trials of anti-IL-6/IL-6R therapies.
  • No systematic search strategy, meta-analysis or primary data collection is described.

Limitations

  • Stated: many questions remain, including how sIL-6Rα is generated, the mechanism of STAT3–NF-κB synergy, and the genetic/environmental factors that destabilize the IL-6 Amp; current knowledge is insufficient to predict disease end stage or detailed process.
  • Stated: more study is needed on interactions among pro-inflammatory molecules and on real-time dynamics of receptor complexes and signaling molecules.
  • Evident from the text: as a narrative review, it does not systematically assess study quality or bias, and many mechanistic conclusions derive from mouse models and in vitro systems rather than human validation.

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

Integrity signals

Registry

Crossref · 10.1093/intimm/dxaa078

Cites

382 of 382 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

220 of 329 cited sources checked · 90 supported · 0 flagged · accuracy not yet measured

Show all 130 claims

  • It may state two separate claims as one. 78
  • Probably not a substantial claim. 7
82 of 82
  • The authors state this as an assumption.

    The same cause can induce both RA and IL-6 expression.

    “Assuming that the same cause can induce both RA and IL-6 expression, such an intimate relationship could be explained.”
1 of 1

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.

  • Figure caption reverses the stated effect of M2 macrophages and MDSCs

    Minor

    The Figure 2 caption describes M2 macrophages and MDSCs as having anti-tumor immunity effects, whereas the main text says both suppress tumor immunity.

  • Murine gp130 mutation is labeled Y759F instead of Y757F

    Minor

    The paper identifies Y757F as the mutation in murine gp130, but later calls the mutation in gp130Y757F/Y757F mice Y759F.

2 of 2

Citations

Cites

Items 201–382 of 382

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8 of the 390 references couldn’t be matched to a known paper.

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Metadata

Authors
Hirano, T.
Affiliations
Hokkaido University (JP)
Corresponding author
Hirano, Toshio
Venue
International Immunology
Published
2020-12-18
Volume
33
Issue
3
Pages
127-148
ISSN
  • 0953-8178 (ISSN-L)
  • 1460-2377
OpenAlex
W3112344668
Cited by
1,453
References
390
Citations by year
2026: 246 · 2025: 394 · 2024: 326 · 2023: 273 · 2022: 165 · 2021: 49
FWCI
39.33
Type
journal article
Language
en
Open access
Locations
  • International Immunology (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (submittedVersion, cc-by-nc)
  • PubMed Central (submittedVersion, cc-by-nc)
  • QST-Repository (National Institutes for Quantum and Radiological Science and Technology) (submittedVersion, cc-by-nc-nd)
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › Cytokine Signaling Pathways and Interactions
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › NF-κB Signaling Pathways
  • Health Sciences › Medicine › Rheumatology › Rheumatoid Arthritis Research and Therapies
Keywords
interleukin-6, chronic inflammation, autoimmunity, cancer, NF-κB, STAT3, cytokine storm, COVID-19 pandemic, senescence, obesity, positive feedback loop, hematopoiesis, bone metabolism
MeSH terms
COVID-19, COVID-19 Drug Treatment, Animals, Humans, Inflammation, Neoplasms, Autoimmunity, Interleukin-6, STAT3 Transcription Factor

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