RJ is interesting because it both stimulates AMPK and has a weak KDAC/HDAC inhibitor inter alia.
chatGPT(5.6paid)
Paper
Nakagawa, Okamoto & Okumura (2026), “Royal jelly suppresses senescence-associated secretory phenotype in senescent human epidermal keratinocytes,” Molecular Biology Reports.
Executive summary
The paper reports that a 24-hour exposure to royal jelly suppresses several inflammatory SASP-associated genes in cultured human epidermal keratinocytes displaying replicative or age-associated senescent phenotypes.
The central result is reasonably convincing at the transcriptional level—particularly for IL-6—but much weaker at the level that matters biologically: actual secretion of SASP proteins. The work supports describing royal jelly as having candidate senomorphic activity in vitro, but does not yet establish a mechanism, efficacy in skin, or rejuvenation.
What the researchers did
They studied several keratinocyte systems:
-
Replicative senescence in normal human epidermal keratinocytes
- Early-passage cells were compared with cells at passage 20.
- Senescence was supported by increased SA-β-gal staining and p16, reduced lamin B1, reduced proliferation and suppression of cell-cycle pathways.
-
A second replicative-senescence model
- Human epidermal keratinocyte progenitors were passaged to passage 10.
-
Chronological-age models
- Keratinocytes obtained from a 75-year-old donor.
- Additional cells from a 56-year-old donor and pooled adult donors.
- These were compared with cells from young donors.
Established senescent cells were treated for 24 hours with lyophilised royal jelly, normally at 1 mg/mL. The preparation was standardised to contain at least:
- 3.8% 10-hydroxy-2-decenoic acid, or 10H2DA;
- 0.6% 10-hydroxydecanoic acid, or 10HDAA.
The researchers measured senescence markers, inflammatory gene expression, IL-6 secretion, cytokine arrays and the transcriptome of senescent versus non-senescent cells.
Main findings
1. The passage model exhibited a credible senescent phenotype
Late-passage keratinocytes showed:
- markedly reduced proliferation;
- increased SA-β-gal positivity;
- increased p16 mRNA and protein;
- reduced lamin B1;
- no significant increase in p21;
- downregulation of E2F and G2/M-associated genes.
RNA sequencing identified 1,035 differentially expressed genes:
- 554 upregulated;
- 481 downregulated.
Inflammatory response and TNF-α/NF-κB gene sets were enriched, while cell-cycle pathways were suppressed. IL-1β, IL-6 and several CXCL chemokines were among the induced genes.
2. Royal jelly did not reverse the core senescent state
After 24 hours, royal jelly did not significantly change:
- SA-β-gal positivity;
- p16 expression;
- p21 expression.
This is consistent with a senomorphic, rather than senolytic or senescence-reversing, effect: the cells remained senescent, but parts of their inflammatory phenotype were attenuated.
3. Royal jelly suppressed selected SASP genes
In the principal replicative-senescence model:
- IL-6 and CXCL10 mRNA were significantly reduced;
- CXCL1 and CXCL2 showed non-significant downward trends;
- IL-6 secretion was significantly reduced.
In the second replicative model:
- IL-6 and CXCL8 mRNA were significantly reduced;
- CXCL1, CXCL2 and CXCL10 only showed non-significant trends;
- IL-6 protein secretion was neither increased by senescence nor significantly reduced by royal jelly.
In cells from the 75-year-old donor:
- IL-6, CXCL1, CXCL2 and SERPINE1 mRNA were elevated and significantly reduced by royal jelly;
- CXCL8 reduction missed significance;
- IL-6 protein reduction also missed significance, with P = 0.081.
IL-6 mRNA was additionally reduced in the 56-year-old and pooled-adult donor cells.
Novelty
The genuinely new contribution is fairly specific:
Royal jelly can acutely suppress parts of the endogenous SASP transcriptional programme in already-senescent human keratinocytes, without removing the cells or reversing their basic senescence markers.
Previous work from the same group had shown that continuous royal-jelly exposure during prolonged culture could delay the emergence of senescence. This paper asks a different question: can royal jelly act after senescence is already established?
Additional useful elements are:
- replication in two keratinocyte culture systems;
- limited validation using cells from chronologically older donors;
- demonstration that the effect is not explained by selective toxicity;
- separation of SASP suppression from reversal of p16/SA-β-gal-positive senescence.
The paper therefore advances royal jelly from a proposed senescence-preventive treatment to a proposed senomorphic treatment.
However, the conceptual novelty is modest. Royal jelly and its fatty acids were already known to suppress IL-6 and NF-κB-associated inflammatory responses. Much of the observed effect could therefore represent a familiar anti-inflammatory action demonstrated in senescent keratinocytes rather than discovery of a novel senescence-specific pathway.
Strengths
- The study treats established senescent cells rather than exposing cells throughout the senescence-induction period.
- It uses multiple keratinocyte models rather than relying exclusively on one cell culture.
- The main model is reasonably well characterised using proliferation, SA-β-gal, p16, lamin B1 and transcriptomics.
- The absence of effects on p16 and SA-β-gal supports the senomorphic interpretation.
- IL-6 was examined at both mRNA and protein levels.
- The authors acknowledge donor heterogeneity and the inconsistency between gene expression and secreted protein results.
- The royal-jelly preparation was partially chemically standardised.
Critical assessment
1. The mechanistic claims are not experimentally demonstrated
The authors repeatedly propose that royal jelly acts through:
- inhibition of TNF-α/NF-κB signalling;
- inhibition of p38/JNK;
- activation of Nrf2;
- reduction of oxidative stress;
- synergistic action of multiple royal-jelly constituents.
But they did not directly measure:
- NF-κB nuclear translocation or transcriptional activity;
- IκB degradation or phosphorylation;
- p38 or JNK phosphorylation;
- Nrf2 activation;
- NQO1 induction in these experiments;
- reactive oxygen species or oxidative damage;
- TNF-α pathway activity after royal-jelly treatment.
The RNA-seq comparison establishes that senescence is associated with inflammatory/NF-κB-related transcription. It does not by itself demonstrate that royal jelly inhibits NF-κB. Indeed, the paper does not appear to present comprehensive RNA sequencing of the royal-jelly-treated cells.
Consequently, the mechanistic conclusion should be:
Royal jelly suppresses selected SASP-associated transcripts through an unidentified mechanism consistent with, but not demonstrated to involve, NF-κB inhibition.
The abstract’s claim that royal jelly reduces oxidative stress is particularly under-supported by the reported experiments.
2. Evidence for suppressing the secretory phenotype is limited
A SASP is fundamentally a secreted phenotype, not merely a set of mRNA levels. Yet significant suppression of secreted IL-6 was demonstrated only in the principal replicative model.
It was not significant in:
- the second replicative model;
- the 75-year-old donor cells.
The broad cytokine array appears principally to characterise senescence, rather than rigorously establish the effects of royal jelly on the entire secretome. There is no quantitative mass-spectrometry secretome analysis or multiplex validation of numerous proteins.
The strongest conclusion is therefore that royal jelly suppresses SASP-related gene expression, with preliminary evidence for suppression of SASP protein secretion.
Calling it a “potent multitarget senomorphic agent” goes beyond the protein-level evidence.
3. The chronological-age validation is weaker than it sounds
Cells obtained from older donors are not automatically senescent cells. They can contain a mixture of:
- genuinely senescent cells;
- slowly proliferating cells;
- differentiated cells;
- stressed cells;
- cells altered by isolation and culture.
The cells from the young and older donors were not necessarily matched for:
- anatomical skin site;
- donor sex;
- isolation conditions;
- passage history;
- vendor;
- culture medium;
- environmental exposure.
The 75-year-old cells were purchased from a different supplier from some of the other keratinocytes. These differences can confound age comparisons.
Furthermore, some adult cells showed only trends rather than significant age-associated increases in IL-6 and other SASP genes. Showing that royal jelly reduces IL-6 in an adult donor culture is not the same as showing that it selectively acts on senescent cells within that culture.
4. The main replicative model is not quite fully arrested
The authors selected passage-20 cells “just before growth arrest”; complete arrest occurred around passages 22–23. Thus, the principal model may contain a substantial fraction of pre-senescent or severely replication-stressed cells rather than a uniformly established senescent population.
Single-cell analysis, EdU incorporation, Ki-67 staining or durable non-proliferation after washout would have clarified the cellular composition.
5. Royal jelly is an undefined mixture
Only two fatty-acid
Overall assessment
This paper provides credible preliminary evidence that royal jelly can acutely reduce parts of the senescence-associated secretory phenotype (SASP) in cultured human keratinocytes. Its strongest result is suppression of IL-6 transcription—and, in one replicative-senescence model, IL-6 protein secretion—without killing the cells or reversing their growth arrest.
However, the paper does not establish that royal jelly is a potent skin senomorphic in vivo, nor does it experimentally demonstrate the proposed NF-κB/Nrf2 mechanism. The fairest conclusion is:
Royal jelly has anti-inflammatory or candidate senomorphic activity in cultured keratinocytes, but its mechanism, active constituent, functional benefit and clinical relevance remain undetermined.
Summary
Nakagawa and colleagues examined whether royal jelly suppresses inflammatory signalling from already-senescent epidermal keratinocytes.
Experimental models
They used three related systems:
-
Replicatively aged normal human epidermal keratinocytes
- Early-passage cells served as non-senescent controls.
- Passage-20 cells, just before complete proliferative arrest, were treated as replicatively senescent.
-
A second replicative model
- Human epidermal keratinocyte progenitors were passaged until proliferation declined.
-
Keratinocytes from chronologically older donors
- Principally a 75-year-old donor.
- Further validation included a 56-year-old donor and pooled adult-donor cells.
Established senescent cells were exposed for 24 hours to freeze-dried royal jelly, generally at 1 mg/mL. The product was standardised to contain at least 3.8% 10-hydroxy-2-decenoic acid and 0.6% 10-hydroxydecanoic acid.
Characterisation of senescence
The passage-20 model showed:
- markedly increased SA-β-gal staining;
- increased p16INK4a;
- reduced lamin B1;
- little or no increase in p21;
- reduced E2F- and G2/M-associated transcription;
- increased inflammatory and SASP-related transcription.
RNA sequencing identified 1,035 differentially expressed genes compared with early-passage cells:
- 554 upregulated;
- 481 downregulated.
The senescent cells showed enrichment of:
- inflammatory-response genes;
- TNF-α/NF-κB-associated genes;
- IL-1β, IL-6, CXCL1, CXCL2, CXCL3 and CXCL8;
- a broader secreted cytokine/chemokine profile.
Thus, the authors established a predominantly p16-high, inflammatory replicative-senescence phenotype.
Effects of royal jelly
Royal jelly produced a dose-dependent reduction in IL-6 mRNA, with 1 mg/mL selected for subsequent experiments.
Importantly, 24-hour treatment did not materially alter:
- SA-β-gal positivity;
- p16INK4a;
- p21;
- the underlying senescent state.
It therefore did not appear to be senolytic or to reverse growth arrest.
In the main replicative model, royal jelly:
- significantly reduced IL-6 and CXCL10 mRNA;
- produced non-significant trends for lower CXCL1 and CXCL2;
- significantly reduced secreted IL-6 protein.
In the second replicative model:
- IL-6 and CXCL8 mRNA were reduced;
- but secreted IL-6 was neither increased by senescence nor reduced by royal jelly.
In 75-year-old donor cells:
- IL-6, CXCL1, CXCL2 and SERPINE1 mRNA were elevated relative to young cells;
- royal jelly reduced these transcripts;
- CXCL8 reduction narrowly missed significance;
- reduction of secreted IL-6 also missed significance, at P = 0.081.
IL-6 transcription was additionally reduced in the 56-year-old and pooled-adult cells.
What is genuinely novel?
1. Treatment of established rather than developing senescence
An earlier 2024 study had reported that prolonged royal-jelly exposure during culture delayed keratinocyte senescence. This paper instead added royal jelly for only 24 hours after a senescent phenotype had developed.
That distinction is meaningful:
- the earlier work suggested a preventive or geroprotective effect;
- this work suggests acute modification of the secretory phenotype of cells that remain senescent.
2. Identification of royal jelly as a candidate keratinocyte senomorphic
The combination of:
- reduced SASP-associated expression;
- no reduction in SA-β-gal;
- no reduction in p16;
- no evidence of selective senescent-cell death;
supports the narrower claim that royal jelly may be senomorphic rather than senolytic.
3. Replication across several keratinocyte preparations
The IL-6 transcriptional effect was observed across:
- two replicative-senescence systems;
- a 75-year-old donor;
- a 56-year-old donor;
- pooled adult donors.
That is better than demonstrating the effect in one immortalised cell line.
4. Transcriptomic description of the keratinocyte model
RNA sequencing provided a reasonably broad description of the senescent state, showing simultaneous:
- suppression of cell-cycle programmes;
- activation of TNF/NF-κB-associated inflammation;
- induction of multiple SASP components.
This confirms that the treatment was being tested against endogenous senescence-associated inflammation rather than an acute LPS or cytokine challenge.
Critique
Strengths
The paper has several good design features:
- It treats already-established senescence.
- It distinguishes SASP suppression from reversal of senescence.
- It uses primary human keratinocytes rather than only transformed cells.
- It examines transcription and, in some experiments, secreted protein.
- It includes an initial dose-response experiment.
- It acknowledges donor heterogeneity and some important limitations.
- The lack of a change in p16 or SA-β-gal makes the senomorphic interpretation more coherent.
Nevertheless, the conclusions considerably outrun the data.
1. The evidence at protein level is weak and inconsistent
The clinically relevant SASP is the material actually secreted from cells, not merely its mRNA.
A significant reduction in secreted IL-6 was found only in the principal replicative-senescence model. It was not reproduced convincingly in the other models:
- no effect on IL-6 secretion in the second replicative model;
- only a non-significant trend in the 75-year-old cells;
- no quantitative validation of most other SASP proteins by ELISA or an equivalent assay.
Consequently, the paper establishes a reasonably reproducible effect on IL-6 gene expression, but not yet a reproducible, broad suppression of the secreted SASP.
Calling royal jelly a “potent multitarget senomorphic agent” is therefore premature.
2. NF-κB inhibition is inferred, not demonstrated
The authors propose that royal jelly acts through TNF-α/NF-κB, p38/JNK and Nrf2 pathways. But the study does not appear to measure:
- NF-κB nuclear translocation;
- p65 phosphorylation;
- IκB degradation;
- NF-κB reporter activity;
- p38 or JNK phosphorylation;
- Nrf2 nuclear localisation;
- NQO1 induction after treatment;
- reactive oxygen species or oxidative damage.
RNA sequencing characterised the difference between young and senescent cells, showing that NF-κB-related programmes were associated with senescence. That does not demonstrate that royal jelly suppressed SASP through NF-κB.
Similarly, the abstract’s statement that royal jelly reduces oxidative stress is not directly supported by an oxidative-stress measurement in this study.
3. “Senomorphic” is not cleanly distinguished from “anti-inflammatory”
If a substance suppresses IL-6 and chemokines in any inflammatory cell, it may simply be an anti-inflammatory agent. To establish senescence-selective or senescence-contextual activity, the authors should have compared royal jelly in:
- senescent keratinocytes;
- non-senescent keratinocytes;
- non-senescent cells stimulated with TNF-α or another inflammatory stimulus.
Without this comparison, the findings show suppression of inflammatory transcription in senescent cells, but not that royal jelly targets a process distinctive to senescence.
The authors recognise this conceptual overlap, but their experiments do not resolve it.
4. The active substance is unknown
Royal jelly is a complex and variable mixture of:
- proteins and peptides;
- sugars;
- fatty acids;
- minerals and other constituents.
Only two fatty acids were standardised, and only one royal-jelly lot appears to have been tested. There was no fractionation or comparison with purified:
- 10H2DA;
- 10HDAA;
- major royal-jelly proteins;
- lipid-depleted or protein-depleted royal jelly.
Therefore, the paper cannot identify the active constituent or demonstrate the claimed synergy between multiple constituents. Batch-to-batch reproducibility is also unknown.
5. The replicative-senescence model is imperfect
The primary model used passage-20 cells before complete proliferative arrest, rather than the passage-22/23 cells that had stopped proliferating for approximately a month.
Although passage-20 cells clearly showed several senescence markers, the population may have contained:
- genuinely senescent cells;
- slowly cycling cells;
- stressed or differentiating keratinocytes.
Keratinocytes also undergo passage-associated differentiation and culture adaptation, which can overlap transcriptionally with senescence. Direct measurements of proliferation, EdU incorporation, clonogenic recovery and irreversible arrest would have strengthened the model.
6. Chronological-age comparisons are confounded
Young and older cells came from different donors and, in some cases, different suppliers or preparations. Differences attributed to donor age could therefore reflect:
- donor genetics;
- anatomical biopsy site;
- sex;
- culture history;
- isolation procedure;
- passage number;
- supplier-specific media;
- pooled versus individual samples.
The 75-year-old preparation is especially useful as a validation system, but one elderly donor cannot establish a general age-related effect. The additional adult preparations help, yet the effective biological donor number remains small.
7. Limited sample size and possible pseudoreplication
Most results represent only three to five “independent experiments.” It is not always clear whether these are:
- independent donors;
- independent cell isolations;
- separate passages from the same donor;
- technical or culture replicates.
Repeated experiments using cells from the same donor increase experimental precision but do not substitute for biological replication across people. Statistical inference about human ageing should be based on donor as the biological unit.
The numerous individual gene comparisons also increase the risk of false-positive findings, particularly where simple t-tests were used without comprehensive multiple-testing correction outside RNA-seq.
8. No functional demonstration that the altered medium is less harmful
The central biological argument is that suppressing keratinocyte SASP should protect neighbouring cells and preserve epidermal homeostasis. But the paper does not test conditioned medium in:
- young keratinocytes;
- epidermal stem/progenitor cells;
- fibroblasts;
- immune cells;
- wound-healing or epidermal-barrier models.
A strong functional experiment would ask whether conditioned medium from royal-jelly-treated senescent cells causes less:
- paracrine senescence;
- stem-cell dysfunction;
- inflammatory signalling;
- barrier impairment.
Without such an experiment, reduced cytokine transcription is a biomarker result rather than evidence of tissue rejuvenation.
9. Exposure and clinical translation are unclear
The cells were exposed directly to 1 mg/mL royal jelly. The paper does not establish:
- whether this concentration is achievable in viable epidermal layers after topical application;
- whether the active molecules cross the stratum corneum;
- whether digestion or oral administration produces relevant systemic exposure;
- whether prolonged exposure is safe;
- whether royal-jelly allergens could provoke cutaneous inflammation.
Royal jelly can cause allergic reactions, particularly in people with atopy or asthma, making clinical safety more complicated than the paper’s comparison with rapamycin or metformin suggests.
10. Commercial conflict deserves weight
All authors are employees of Yamada Bee Company, which supplied the royal jelly and has a commercial interest in royal-jelly products. This does not invalidate the experiments, but it raises the importance of:
- independent replication;
- blinded analysis;
- preregistered endpoints;
- testing multiple batches;
- full release of RNA-seq data.
The RNA-seq dataset is available only on reasonable request rather than deposited in a public repository, which limits immediate reproducibility.
Interpretation of the central claim
| Claim | Evidence level |
|---|---|
| Royal jelly reduces IL-6 mRNA in cultured senescent keratinocytes | Fairly strong |
| Royal jelly reduces multiple SASP transcripts | Moderate |
| Royal jelly reduces the secreted SASP broadly | Weak |
| Royal jelly is not senolytic over 24 hours | Supported, within the assays used |
| Royal jelly reverses cellular senescence | Not supported |
| NF-κB inhibition mediates the effect | Plausible but unproven |
| Royal jelly reduces oxidative stress in these experiments | Not directly demonstrated |
| Royal jelly rejuvenates human skin | Not established |
| Royal jelly is safer or more effective than rapamycin/metformin | Not tested |
Bottom line
This is a useful hypothesis-generating in-vitro paper. The new and credible observation is that acute royal-jelly exposure can suppress IL-6 and some other inflammatory transcripts in primary keratinocytes that retain an established senescent phenotype.
The work is considerably less decisive than its language suggests. It neither identifies the active ingredient nor establishes the mechanism, broad protein-level SASP suppression, functional protection of neighbouring cells, skin penetration or human efficacy. A better title-level interpretation would be:
Royal jelly acutely suppresses selected inflammatory components of the SASP in cultured human keratinocytes.
The most valuable next experiment would be a donor-powered, blinded 3D human-skin study measuring the full secretome and testing whether conditioned medium from treated senescent keratinocytes loses its ability to induce paracrine senescence or impair epidermal regeneration.