LL-37 · research summary

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

PloS one · 2026. Summary drawn from the study's full text. Each statement is followed by the exact sentence it comes from. This is a research summary, not medical advice.

Study type

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

Subjects

Men diagnosed with obstructive sleep apnea (OSA) and healthy male controls
“The cohort included 58 men diagnosed with OSA and 20 men classified as non-OSA based on PSG findings.”

Sample size

78 participants (58 with OSA, 20 controls)
“The associations between pLL-37 levels, demographic characteristics, and polysomnographic (PSG) parameters were assessed in 58 individuals with OSA and 20 healthy controls.”

Duration

Cross-sectional assessment with a sub-study of approximately 3 months for CPAP treatment
“With informed consent, blood samples were obtained from these patients before and after the nCPAP treatment for a mean of approximately 3 months, and pLL-37 levels were measured.”

Reported findings

Plasma LL-37 levels were significantly lower in individuals with moderate-to-severe OSA (AHI ≥ 15) compared to those with no-to-mild OSA (AHI < 15).
“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).”
Plasma LL-37 levels were negatively correlated with age, arousal index, AHI, and oxygen desaturation index, and positively correlated with deep sleep stages and oxygen saturation.
“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.”
Percentage of Stage N1 sleep and AHI were identified as independent factors associated with plasma LL-37 levels in multiple regression analysis.
“In the revised model, %Stage N1 (p = 0.045) and AHI (p = 0.014) remained significantly associated with pLL-37, suggesting that these variables are independently related to pLL-37 levels.”

Limitations stated by the authors

The cross-sectional design precludes causal inference, and the study only included adult males with a single blood sample collection time.
“First, the cross-sectional design precludes conclusions regarding causality.”

Source: PubMed 42685028 · DOI 10.1371/journal.pone.0355855 · all study summaries

Reported findings

Plasma LL-37 levels were significantly lower in individuals with moderate-to-severe OSA (AHI ≥ 15) compared to those with no-to-mild OSA (AHI < 15).

“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).”

Plasma LL-37 levels were negatively correlated with age, arousal index, AHI, and oxygen desaturation index, and positively correlated with deep sleep stages and oxygen saturation.

“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.”

Percentage of Stage N1 sleep and AHI were identified as independent factors associated with plasma LL-37 levels in multiple regression analysis.

“In the revised model, %Stage N1 (p = 0.045) and AHI (p = 0.014) remained significantly associated with pLL-37, suggesting that these variables are independently related to pLL-37 levels.”