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Study · Measured the body's own peptide · 2021

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Vitamin D Modulation of the Innate Immune Response to Paediatric Respiratory Pathogens Associated with Acute Lower Respiratory Infections.

Bleakley AS, Licciardi PV, Binks MJ

Nutrients19 Jan 2021Cited by 21 (Europe PMC)

PMID33478006 (opens in a new tab)PMCIDPMC7835957 (opens in a new tab)DOI10.3390/nu13010276 (opens in a new tab)PepBankPUB-33478006
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Summary

Vitamin D is an essential component of immune function and childhood deficiency is associated with an increased risk of acute lower respiratory infections (ALRIs). Globally, the leading childhood respiratory pathogens are Streptococcus pneumoniae, respiratory syncytial virus and the influenza virus. There is a growing body of evidence describing the innate immunomodulatory properties of vitamin D during challenge with respiratory pathogens, but recent systematic and unbiased synthesis of data is lacking, and future research directions are unclear. We therefore conducted a systematic PubMed literature search using the terms "vitamin D" and "Streptococcus pneumoniae" or "Respiratory Syncytial Virus" or "Influenza". A priori inclusion criteria restricted the review to in vitro studies investigating the effect of vitamin D metabolites on human innate immune cells (primary, differentiated or immortalised) in response to stimulation with the specified respiratory pathogens. Eleven studies met our criteria. Despite some heterogeneity across pathogens and innate cell types, vitamin D modulated pathogen recognition receptor (PRRs: Toll-like receptor 2 (TLR2), TLR4, TLR7 and nucleotide-binding oligomerisation domain-containing protein 2 (NOD2)) expression; increased antimicrobial peptide expression (LL-37, human neutrophil peptide (HNP) 1-3 and β-defensin); modulated autophagosome production reducing apoptosis; and modulated production of inflammatory cytokines (Interleukin (IL) -1β, tumour necrosis factor-α (TNF-α), interferon-ɣ (IFN-ɣ), IL-12p70, IFN-β, Regulated on Activation, Normal T cell Expressed (RANTES), IL-10) and chemokines (IL-8 and C-X-C motif chemokine ligand 10 (CXCL10)). Differential modulation of PRRs and IL-1β was reported across immune cell types; however, this may be due to the experimental design. None of the studies specifically focused on immune responses in cells derived from children. In summary, vitamin D promotes a balanced immune response, potentially enhancing pathogen sensing and clearance and restricting pathogen induced inflammatory dysregulation. This is likely to be important in controlling both ALRIs and the immunopathology associated with poorer outcomes and progression to chronic lung diseases. Many unknowns remain and further investigation is required to clarify the nuances in vitamin D mediated immune responses by pathogen and immune cell type and to determine whether these in vitro findings translate into enhanced immunity and reduced ALRI in the paediatric clinical setting.
CC BYText from Europe PMC. Highlighted sentences are the source of results.

Results from this study1

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

Natural levels measured1

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. 01LabEndogenous levelOther designMechanism

    In a systematic review of in vitro studies of human innate immune cells exposed to respiratory pathogens, vitamin D metabolites increased expression of the body's own LL‑37.

    In plain wordsIn lab studies of human immune cells, vitamin D raised the cells' own LL‑37 production when they met respiratory germs.

    Peptide
    LL-37
    Outcome
    IncreaseAntimicrobial peptide expression after vitamin D
    Study

    humann: not reported in source

    human innate immune cells stimulated with respiratory pathogens
    Outcome group
    Immune response · Immune and inflammation

    Source sentences

    Summary
    increased antimicrobial peptide expression (LL-37, human neutrophil peptide (HNP) 1-3 and β-defensin
    1 context sentence
    Summary · context
    A priori inclusion criteria restricted the review to in vitro studies investigating the effect of vitamin D metabolites on human innate immune cells (primary, differentiated or immortalised) in response to stimulation with the specified respiratory pathogens.

    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

    9 Oct 2026, 18:17 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, 02:57 UTC

    First added · source update from Europe PMC

Subjects

Terms as the source lists them.

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