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Study · Measured the body's own peptide · 2026

11 results

Plasma levels of antimicrobial peptide LL-37 as a biomarker of sleep quality in patients with obstructive sleep apnea: A clinical observational study.

Yamaguchi T, Hosokawa K, Mineta T, Hosokawa R, Odawara S, Chiba R, Asanuma K, Toyomaki S, Sato M, Takahashi F, Sakurai S, Takahashi K, Nishijima T

PloS one2 Sept 2026

PMID42685028 (opens in a new tab)PMCIDPMC13537548 (opens in a new tab)DOI10.1371/journal.pone.0355855 (opens in a new tab)PepBankPUB-42685028
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Summary

ObjectivesObstructive sleep apnea (OSA) is characterized by systemic inflammation, intermittent hypoxemia, and immune dysregulation and has been associated with increased susceptibility to viral infections. In this study, we aimed to evaluate plasma concentrations of the antimicrobial peptide cathelicidin LL-37 (pLL-37) in individuals with OSA.MethodsThe associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls. Participants were stratified into two groups stratified by apnea-hypopnea index (AHI): AHI < 15 and AHI ≥ 15. Multiple regression analysis was conducted to identify independent predictors of pLL-37.ResultsSignificant negative correlations were observed between pLL-37 levels and age, percentage of Stage N1 sleep based on PSG data (%Stage N1), arousal index, AHI, and oxygen desaturation index. Conversely, significant positive correlations were identified between pLL-37 levels and %Stage N3, percentage of rapid eye movement sleep (%Stage REM), mean percentage of peripheral oxygen saturation (%SpO2 mean), and %SpO2 minimum. Mean pLL-37 level was significantly higher in the AHI < 15 group (75.3 ± 29.3 ng/L) than in the AHI ≥ 15 group (47.1 ± 18.3 ng/L). Multiple regression analysis identified %Stage N1 as an independent factor associated with pLL-37.ConclusionspLL-37 levels were significantly reduced in individuals with severe OSA than in healthy controls. %Stage N1 was independently associated with pLL-37 levels, suggesting a decline with worsening oxygen desaturation. These findings suggest pLL-37 may serve as a biomarker for sleep quality and the severity of impaired oxygenation during sleep with implications for immune vulnerability and infection risk in OSA.
CC BYText from Europe PMC. Highlighted sentences are the source of results.

Results from this study11

No result from this study comes from a test of the peptide.

Natural levels measured11

These results measure the body's own peptide. Nobody was given the peptide. They are not evidence about taking it. They are left out of key results, evidence counts and charts.

  1. 01HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated negatively with age.

    In plain wordsLinked to older age, the body's own LL‑37 levels in blood were lower.

    Peptide
    LL-37
    Outcome
    DecreasepLL-37 versus age
    Study

    n = 78

    Outcome group
    Aging markers · Aging and longevity

    Source sentences

    Summary
    Significant negative correlations were observed between pLL-37 levels and age, percentage of Stage N1 sleep based on PSG data (%Stage N1), arousal index, AHI, and oxygen desaturation index.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  2. 02HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated negatively with the percentage of Stage N1 sleep.

    In plain wordsLinked to more light stage N1 sleep, the body's own LL‑37 levels in blood were lower.

    Peptide
    LL-37
    Outcome
    DecreasepLL-37 versus %Stage N1 sleep
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Significant negative correlations were observed between pLL-37 levels and age, percentage of Stage N1 sleep based on PSG data (%Stage N1), arousal index, AHI, and oxygen desaturation index.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  3. 03HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated negatively with the arousal index.

    In plain wordsLinked to more sleep arousals, the body's own LL‑37 levels in blood were lower.

    Peptide
    LL-37
    Outcome
    DecreasepLL-37 versus arousal index
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Significant negative correlations were observed between pLL-37 levels and age, percentage of Stage N1 sleep based on PSG data (%Stage N1), arousal index, AHI, and oxygen desaturation index.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  4. 04HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated negatively with the apnea-hypopnea index.

    In plain wordsLinked to more severe sleep apnea, the body's own LL‑37 levels in blood were lower.

    Peptide
    LL-37
    Outcome
    DecreasepLL-37 versus AHI
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Significant negative correlations were observed between pLL-37 levels and age, percentage of Stage N1 sleep based on PSG data (%Stage N1), arousal index, AHI, and oxygen desaturation index.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  5. 05HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated negatively with the oxygen desaturation index.

    In plain wordsLinked to more oxygen drops during sleep, the body's own LL‑37 levels in blood were lower.

    Peptide
    LL-37
    Outcome
    DecreasepLL-37 versus oxygen desaturation index
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Significant negative correlations were observed between pLL-37 levels and age, percentage of Stage N1 sleep based on PSG data (%Stage N1), arousal index, AHI, and oxygen desaturation index.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  6. 06HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated positively with the percentage of Stage N3 sleep.

    In plain wordsLinked to more deep stage N3 sleep, the body's own LL‑37 levels in blood were higher.

    Peptide
    LL-37
    Outcome
    IncreasepLL-37 versus %Stage N3 sleep
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Conversely, significant positive correlations were identified between pLL-37 levels and %Stage N3, percentage of rapid eye movement sleep (%Stage REM), mean percentage of peripheral oxygen saturation (%SpO2 mean), and %SpO2 minimum.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  7. 07HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated positively with the percentage of REM sleep.

    In plain wordsLinked to more REM sleep, the body's own LL‑37 levels in blood were higher.

    Peptide
    LL-37
    Outcome
    IncreasepLL-37 versus %Stage REM sleep
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Conversely, significant positive correlations were identified between pLL-37 levels and %Stage N3, percentage of rapid eye movement sleep (%Stage REM), mean percentage of peripheral oxygen saturation (%SpO2 mean), and %SpO2 minimum.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  8. 08HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated positively with mean peripheral oxygen saturation.

    In plain wordsLinked to higher average blood oxygen during sleep, the body's own LL‑37 levels in blood were higher.

    Peptide
    LL-37
    Outcome
    IncreasepLL-37 versus mean SpO2
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Conversely, significant positive correlations were identified between pLL-37 levels and %Stage N3, percentage of rapid eye movement sleep (%Stage REM), mean percentage of peripheral oxygen saturation (%SpO2 mean), and %SpO2 minimum.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  9. 09HumanEndogenous levelObservational studyOther

    In individuals with OSA and healthy controls, plasma LL‑37 correlated positively with minimum peripheral oxygen saturation.

    In plain wordsLinked to a higher lowest blood oxygen during sleep, the body's own LL‑37 levels in blood were higher.

    Peptide
    LL-37
    Outcome
    IncreasepLL-37 versus minimum SpO2
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Conversely, significant positive correlations were identified between pLL-37 levels and %Stage N3, percentage of rapid eye movement sleep (%Stage REM), mean percentage of peripheral oxygen saturation (%SpO2 mean), and %SpO2 minimum.
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  10. 10HumanEndogenous levelObservational studyOther

    In multiple regression, the percentage of Stage N1 sleep was an independent factor associated with plasma LL‑37.

    In plain wordsLight stage N1 sleep was independently linked to the body's own LL‑37 levels in blood.

    Peptide
    LL-37
    Outcome
    Not applicableIndependent predictor of pLL-37
    Study

    n = 78

    Outcome group
    Sleep · Sleep

    Source sentences

    Summary
    Multiple regression analysis identified %Stage N1 as an independent factor associated with pLL-37.
    2 context sentences
    Summary · context
    Multiple regression analysis was conducted to identify independent predictors of pLL-37.
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

  11. 11HumanEndogenous levelObservational studyOther

    Mean plasma LL‑37 was lower in the group with AHI of 15 or more than in the group with AHI below 15.

    In plain wordsPeople with more severe sleep apnea had lower levels of the body's own LL‑37 than people with milder apnea.

    Peptide
    LL-37
    Outcome
    DecreasepLL-37 in AHI <15 versus AHI >=15
    Study

    n: not reported in source

    Comparator
    AHI < 15 group
    Outcome group
    Sleep · Sleep

    Measurements

    pLL-37
    75.3 ng/L
    AHI < 15
    pLL-37
    47.1 ng/L
    AHI >= 15

    Source sentences

    Summary
    Mean pLL-37 level was significantly higher in the AHI < 15 group (75.3 ± 29.3 ng/L) than in the AHI ≥ 15 group (47.1 ± 18.3 ng/L).
    1 context sentence
    Summary · context
    The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.

    This result measures the body's own LL-37. Nobody was given the peptide. It is not evidence about taking it.

AI wrote and checked these results. AI can make mistakes, so check important results against the source.

Version history

PepBank keeps every version of the data on this study. Status changes from Retraction Watch, Europe PMC and Crossref are listed with their source.

  1. Version 3Current

    11 Oct 2026, 00:50 UTC

    Study results updated

  2. Version 2

    9 Oct 2026, 03:03 UTC

    Study data updated · source update from Europe PMC

  3. Version 1

    9 Oct 2026, 02:56 UTC

    First added · source update from Europe PMC

Subjects

Terms as the source lists them.

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