28-residue secretin-family neuropeptide and immunomodulator

Our opinion on this compoundNiche research probe

43/100

A 1970-vintage VPAC reference probe with a genuinely interesting mechanism undermined by mixed clinical results and anecdote-heavy indications

Look, VIP is a genuinely interesting peptide that has spent five decades accumulating a reputation that slightly outpaces its evidence. Sami Said and Viktor Mutt isolated it from porcine duodenum in 1970, which should tell you something about where we are on the novelty axis. The core molecule is not a new discovery. What keeps it relevant is the mechanism: VPAC1 and VPAC2 are widely expressed GPCRs and the cAMP-mediated pleiotropy VIP engages, covering vasodilation, bronchodilation, cytokine suppression (TNF, IL-6, IL-12), and Treg induction simultaneously, is the kind of multi-target pharmacology that makes immunologists pay attention. Thats not trivial. The problem is that knowing a mechanism and converting it into clinical utility are different things, and VIP’s clinical story is mostly a story of near-misses.

The highest-profile clinical program is Aviptadil for pulmonary arterial hypertension. Phase 3 data exists, which is more than most peptides in this library can say, but the results came back mixed. Emergency use authorization in some jurisdictions during COVID-19 ARDS was real, but jurisdictionally narrow and not replicated into approval. The CIRS protocol, championed by Ritchie Shoemaker as an intranasal spray administered after Marcons eradication, is supported by case-series evidence. Case series. For a compound this old and this studied, that’s a problem. We don’t doubt there are real patients reporting benefit; we do doubt whether the mechanism driving that benefit has been properly characterized in a controlled setting.

What we actually like here is the bench utility. If you’re working on VPAC receptor pharmacology, secretin-family peptide biology, or the immunomodulatory interface between neuropeptides and innate immunity, VIP is the canonical reference compound. There isn’t a clean synthetic alternative that covers VPAC1 and VPAC2 with the same profile. The Treg induction angle, and specifically VIP’s role in shaping the tolerogenic cytokine environment, is an active research question in autoimmune models. The intranasal route creates an interesting local mucosal exposure model even if systemic absorption is limited by the sub-2-minute plasma half-life.

What we don’t like: the CIRS angle is clinically murky enough that it’s hard to separate real pharmacology from protocol mythology. Aviptadil’s mixed Phase 3 is a real mark against translational confidence. And the compound itself, isolated in 1970, has been around long enough that the main VPAC literature is mature rather than growing rapidly. Honestly, the research value here is real but narrow: VPAC probe work and secretin-family mechanistic studies. Outside of that specific lane, the evidence base is thin and the clinical programs have not delivered the clarity investigators would need to prioritize this compound over more focused tools.

Novelty: 30
Mechanism promise: 50
In-category differentiation: 45
Evidence quality: 45
Translational signal: 38
Research bench value: 58

Rationale VIP scores modestly because the compound is more than 50 years old and the VPAC1/VPAC2 pharmacology is well-characterized, but it earns above-floor marks for its multi-target immunomodulatory mechanism and genuine probe utility in the secretin-family receptor literature. The key scoring drag is clinical: Aviptadil’s Phase 3 was mixed, CIRS evidence is case-series only, and the COVID-19 EUA was jurisdictionally narrow and did not translate to broad approval.

28-residue secretin-family neuropeptide and immunomodulator

A 28-amino-acid peptide of the secretin/glucagon family with broad anti-inflammatory and bronchodilator activity, used in CIRS and chronic biotoxin protocols and studied for pulmonary arterial hypertension.

Abstract

Vasoactive Intestinal Peptide (VIP; His-Ser-Asp-Ala-Val-Phe-Thr-Asp-Asn-Tyr-Thr-Arg-Leu-Arg-Lys-Gln-Met-Ala-Val-Lys-Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH2; CAS 40077-57-4; molecular formula C147H237N43O43S; molecular weight 3326.81) is a 28-residue C-terminally amidated peptide originally isolated from porcine duodenum by Sami Said and Viktor Mutt in 1970 as a vasodilator and bronchodilator activity. VIP belongs to the secretin/glucagon/PACAP peptide family and signals through the VPAC1 and VPAC2 G-protein-coupled receptors expressed widely on epithelial, endothelial, smooth muscle, and immune cells. The pharmacological signature is broad: vasodilation and bronchodilation through cAMP elevation in vascular and bronchial smooth muscle, anti-inflammatory effects through suppression of pro-inflammatory cytokine production (TNF, IL-6, IL-12) and induction of regulatory T cell phenotypes, and neuroprotective and anti-apoptotic effects in central nervous system tissue. VIP has been extensively studied as a research tool for VPAC receptor pharmacology and explored clinically for indications including pulmonary arterial hypertension (Aviptadil, Phase 3, mixed results; emergency use authorization for COVID-19 ARDS in some jurisdictions), sarcoidosis, asthma, and Sjogren’s syndrome. In integrative medicine and chronic inflammatory response syndrome (CIRS) protocols, VIP is administered as an intranasal spray after Marcons (multiple antibiotic resistant coagulase negative staphylococci) eradication; the protocol was developed by Ritchie Shoemaker and is supported by case-series evidence rather than randomized trials. The compound is not FDA-approved for any chronic indication; intranasal VIP for CIRS is compounded by specialty pharmacies. Plasma half-life is short (less than 2 minutes); the intranasal route provides direct nasal mucosal exposure with limited systemic absorption.

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The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

Tag: 28-residue secretin-family neuropeptide and immunomodulator

Vasoactive Intestinal Peptide (VIP)

Abstract

Read the full monograph