VIP Peptide Research: Trials, Mechanisms & What the Studies Show
Vasoactive Intestinal Peptide (VIP) is a 28-amino-acid endogenous neuropeptide researched for its potent anti-inflammatory, vasodilatory and immunomodulatory properties. The literature spans respiratory failure, autoimmune disease, gut immunity and neuroimmunology.
Mechanism of action
VIP signals through the VPAC1 and VPAC2 receptors (with cross-reactivity at PAC1), G-protein coupled receptors expressed on vascular smooth muscle, alveolar cells, lymphocytes and neurons — which is why one molecule produces both vascular and immune effects.
On the vascular side it is a potent, selective pulmonary vasodilator, lowering pulmonary artery pressure and total peripheral resistance while improving cardiac output.
On the immune side it acts as a cytokine-like regulator: inhibiting NF-κB, downregulating Th1/Th17 responses, expanding T-regulatory cells and boosting IL-10 production.
In the lung, VIP binds alveolar type II cells — the same cells targeted in ARDS research — where it is studied for preventing cellular apoptosis and blunting pro-inflammatory cytokine cascades.
High receptor densities in the amygdala, hypothalamus and suprachiasmatic nucleus underlie the circadian, fear-extinction and anxiety-regulation literature.
The studies
The strongest human data sits in pulmonary medicine; the autoimmune and gut findings come predominantly from animal models. Aviptadil is the synthetic form of VIP used in registered respiratory trials.
Pulmonary & respiratory
Inhaled VIP in primary pulmonary hypertension
Whether inhaled native VIP improves haemodynamics in primary pulmonary hypertension (PPH).
Pilot study · inhaled native VIP · invasive haemodynamic measurement and oxygen saturation monitoring
- Decreased
- Mean pulmonary artery pressure
- Significantly improved
- Cardiac output
- None significant
- Side effects
- Inhaled VIP decreased mean pulmonary artery pressure and significantly improved cardiac output without negative side effects.
- Oxygen saturation improved alongside the haemodynamic changes.
- The study established VIP as a highly potent, selective pulmonary vasodilator — selective because the inhaled route concentrates the effect in the lung.
Aviptadil in acute hypoxaemic respiratory failure
Whether synthetic VIP (aviptadil) improves outcomes in COVID-19-related hypoxaemic respiratory failure and ARDS.
Large multicentre randomised controlled trial · intravenous aviptadil versus placebo · hypoxaemic respiratory failure
- Aviptadil (synthetic VIP)
- Compound
- FDA Fast Track
- Regulatory status
- Alveolar type II cells
- Target
- Aviptadil received Fast Track designation during the COVID-19 pandemic for treatment of acute respiratory distress syndrome (ARDS).
- The mechanistic rationale was binding to alveolar cells to prevent cellular apoptosis and block pro-inflammatory cytokine storm.
- A large multicentre randomised controlled trial evaluated it in hypoxaemic respiratory failure — the most rigorous human dataset on VIP to date.
Autoimmunity & joint health
Collagen-induced arthritis model
Whether VIP acts as a disease-modifying agent in experimental rheumatoid arthritis.
Collagen-induced arthritis in mice (Delgado et al.) · VIP administration · joint histology and cytokine profiling
- Significantly reduced
- Cartilage destruction
- Significantly reduced
- Bone erosion
- Downregulated
- Inflammatory cytokines
- VIP suppressed collagen-induced arthritis, significantly reducing cartilage destruction, bone erosion and inflammatory cytokines.
- Unlike biologics that block a single pathway, VIP simultaneously downregulated both the autoimmune response and the structural inflammatory cascade.
- Arthritis onset was delayed and joint integrity preserved — the basis for describing it as a disease-modifying candidate in this model.
Immune & gut homeostasis
Intestinal immunity and inflammatory bowel disease
How VIP regulates mucosal immunity and protects gut lining integrity.
Experimental colitis models and mechanistic immunology · T-cell subset and cytokine analysis
- Downregulated
- Th1/Th17 responses
- Increased
- IL-10 (regulatory B cells)
- Inhibited
- NF-κB signalling
- VIP shifted the immune system toward anti-inflammatory states by inhibiting NF-κB and regulating T-regulatory (Treg) cells.
- In gastrointestinal research it downregulated Th1/Th17 inflammatory responses and boosted Interleukin-10 (IL-10) production in regulatory B cells.
- The net effect in these models was protection of gut lining integrity.
Cardiovascular
Systemic VIP infusion haemodynamics
The systemic cardiovascular profile of intravenous native VIP.
Controlled VIP infusion · continuous haemodynamic monitoring · peripheral resistance and contractility measures
- Sustained
- Vasodilation
- Decreased
- Total peripheral resistance
- Temporarily boosted
- LV contractility
- Infusion induced sustained vasodilation and decreased total peripheral resistance.
- Left ventricular contractility was temporarily boosted.
- This systemic profile is why inhaled delivery is preferred in pulmonary research — it localises the vasodilatory effect.
Neuroimmunology & CNS
Neuroprotection, circadian and emotional regulation
VIP's role as a neuroimmune regulator and its CNS distribution effects.
Review papers and mechanistic studies · blood-brain barrier integrity, neurotoxicity models, plasma VIP correlation studies
- Cytokine-like molecule
- Classification
- Integrity maintained
- Blood-brain barrier
- Amygdala, hypothalamus
- CNS sites
- Review papers describe VIP as a cytokine-like molecule that protects neurons from toxic exposure and controls blood-brain barrier integrity.
- It balances the central nervous system during chronic inflammatory conditions such as multiple sclerosis.
- High VIP densities in the amygdala and hypothalamus link normal plasma levels to circadian motor rhythmicity, fear-extinction learning and anxiety regulation.
Storage & handling
VIP is supplied as a lyophilised powder. Keep sealed vials refrigerated or frozen, protected from light and moisture.
Reconstitute with bacteriostatic water directed slowly down the inner wall of the vial and swirl gently until clear. Do not shake — VIP is a fragile 28-amino-acid chain.
Store reconstituted solution at 2-8 °C and use within the stability window set by your lab's standard operating procedures.
All information on this page is provided for laboratory and educational reference only. Peptides Lab SA (PTY) Ltd supplies compounds strictly for in-vitro research use. Nothing here is medical advice, a dosing recommendation, or a claim of human safety or efficacy.