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Immune & Inflammatory

Peptides modulating immune function, inflammation, and antimicrobial defense.

Clinical Overview

Immune & Inflammatory

Peptides modulating immune function, inflammation, and antimicrobial defense.

3 peptides0 FDA-approvedSubcutaneous injection · Oral (PepT1-mediated) · SC · topical · intranasal · Topical (most common) · subcutaneous injection (SC) · mesotherapy · microneedling deliveryLast reviewed · April 22, 2026

Immune and inflammatory peptides span three mechanistic categories — immunomodulators, anti-inflammatory peptides, and antimicrobial host-defense peptides. Thymosin alpha-1 has the most developed clinical evidence in this class.

Mechanism Classes

  • Immunomodulators

    Thymosin alpha-1 is a thymic peptide that modulates T-cell maturation and immune balance. Used internationally for chronic viral infections and immune dysregulation.

  • Anti-inflammatory peptides

    KPV is a tripeptide derived from alpha-MSH with anti-inflammatory effects, studied in inflammatory bowel disease and inflammatory skin conditions. GHK-Cu contributes broad anti-inflammatory gene-expression effects.

  • Antimicrobial host-defense peptides

    LL-37 (cathelicidin) is a human host-defense peptide with broad-spectrum activity against bacteria, fungi, and some viruses. Clinical use remains investigational.

Regulatory Status

FDA-Approved

None FDA-approved in this category.

Investigational / Off-Label

  • Thymosin Alpha-1 (US)
  • KPV
  • LL-37
  • GHK-Cu

Thymosin alpha-1 is approved in 35+ countries (brand name Zadaxin) for hepatitis B, hepatitis C, and as a vaccine adjuvant — but is not FDA-approved in the United States.

Evidence Base

Thymosin alpha-1 has FDA-submitted trials and multi-country approvals. KPV, LL-37, and GHK-Cu remain primarily preclinical or early clinical in Western medicine. No antimicrobial peptide is FDA-approved for systemic infection.

Primary-Literature References

38

Across 3 linked monographs

Prescribing Considerations

  1. 1Caution in patients with active autoimmune disease — immunomodulators can theoretically exacerbate autoimmunity (coordinate with rheumatology / immunology).
  2. 2Baseline immune workup: CBC with differential, CMP, inflammatory markers (CRP, ESR), and disease-specific markers (viral loads, autoimmune serologies) as indicated.
  3. 3Screen for active infections before initiating immunomodulator therapy.
  4. 4For LL-37 or antimicrobial peptide use, limit to well-justified cases with infectious-disease consultation.
  5. 5Track both objective markers and subjective clinical endpoints; recheck labs every 3–6 months on long-term therapy.
  6. 6Discontinue if unexpected disease flares or new autoimmune phenomena emerge.
Peer-reviewed clinical references · last reviewed April 22, 2026PeptidePrescriber · Clinical Reference

Peptides in this category(3)

Clinical monographs for each agent — dosing ranges, safety profile, evidence, and prescribing considerations.

Immune ModulationPreclinicalOral (PepT1-mediated) · SC · topical · intranasal

KPV

Investigational anti-inflammatory therapy for inflammatory bowel disease and other chronic inflammatory conditions (no FDA-approved indication)

Primary indication: Investigational anti-inflammatory therapy for inflammatory bowel disease and other chronic inflammatory conditions (no FDA-approved indication)

KPV is the C-terminal tripeptide (Lys-Pro-Val) of alpha-melanocyte-stimulating hormone (alpha-MSH). Despite its origin, KPV does not act through classical melanocortin receptors (MC1R-MC5R) — its anti-inflammatory effects are mediated by a melanocortin-receptor-independent mechanism. The key molecular pathway is cellular uptake via the proton-coupled oligopeptide transporter PepT1 (SLC15A1), which is normally expressed on the apical surface of small-intestinal enterocytes but is markedly upregulated on inflamed colonic epithelium and on activated immune cells during inflammation. This upregulation of PepT1 on inflamed tissue provides tissue selectivity for KPV delivery. Once internalized, KPV suppresses the nuclear factor-kappa B (NF-kB) signaling cascade — a master regulator of inflammatory gene expression — by inhibiting IkB degradation, reducing nuclear translocation of p65, and attenuating downstream transcription of pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-6, IL-8). Additional reported actions include reduction of neutrophil chemotaxis, attenuation of mast-cell degranulation, and dampening of pro-inflammatory signaling in dendritic cells and macrophages. In preclinical models, KPV demonstrated equal or greater anti-inflammatory potency than full-length alpha-MSH.

Read full guide

1 additional monograph in this category is in clinical review and will be published soon.

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