VIP (Vasoactive Intestinal Peptide)

VIP (Vasoactive Intestinal Peptide) is a 28-amino acid neuropeptide belonging to the secretin/glucagon superfamily, widely distributed throughout the central and peripheral nervous systems, immune tissues, and gastrointestinal tract. VIP acts as a neurotransmitter, neuromodulator, and immunomodulator through two G-protein coupled receptors (VPAC1 and VPAC2). Research demonstrates potent anti-inflammatory properties through inhibition of pro-inflammatory cytokines and promotion of regulatory T-cell function. VIP causes vasodilation, relaxes smooth muscle, stimulates water and electrolyte secretion, and regulates circadian rhythms. Studies indicate neuroprotective effects through multiple mechanisms including inhibition of neuroinflammation and support of neuronal survival. The peptide has shown therapeutic potential in models of autoimmune diseases, inflammatory bowel disease, sepsis, and neurodegenerative conditions. VIP also influences cardiac function, bronchodilation, and pancreatic secretion. Research into VIP and its analogs continues for applications in chronic inflammatory conditions and neurological disorders.

VIP is rapidly degraded in plasma (very short half-life), which complicates delivery. The sarcoidosis and asthma studies are small and dated; the COVID-19 ARDS trials were negative on survival; no VIP formulation is FDA-approved. Neuroprotective claims rest mainly on preclinical data.

28-amino-acid neuropeptide with a very short plasma half-life due to rapid enzymatic degradation; delivered by inhalation or intravenous infusion in trials. Acts via VPAC1/VPAC2 G-protein-coupled receptors to modulate immune function, dilate vessels, and relax smooth muscle (bronchodilation). Stabilized analogs and formulations (e.g., aviptadil) were developed to improve half-life.