KPV (Lys-Pro-Val): what it is, where it comes from, and what the published studies actually tested

What KPV is#

KPV is a tripeptide: three amino acids, lysine, proline and valine, joined in that order. The letters are the single-letter codes for those residues (K, P, V). It is the last three residues, positions 11 to 13, of alpha-melanocyte-stimulating hormone (α-MSH), a thirteen-residue hormone produced from the larger precursor protein pro-opiomelanocortin.^[1][2]

In chemical databases the free peptide has the molecular formula C16H30N4O4, a molecular weight of 342.43 g/mol, CAS registry number 67727-97-3 and PubChem compound identifier 125672.^[3] Research suppliers usually sell it as a lyophilized powder, and the form on a label (free peptide, acetate salt or another salt) changes the mass of material per milligram of peptide; the lot's Certificate of Analysis is where that is stated. The KPV product page lists the identifiers above with the lot records for our own vials.

Why a three-residue fragment was studied at all#

The interest in KPV follows from the interest in its parent. α-MSH is one of the melanocortin peptides, and its biology has been examined in many settings since the 1980s. Researchers asked whether the activity associated with the full thirteen-residue hormone could be traced to a shorter section of it. The C-terminal tripeptide, KPV, was one of the fragments examined, partly because a molecule that small can be synthesised cheaply and partly because small peptides are handled differently by cells: some are moved across membranes by dedicated peptide transporters rather than by receptor binding.^[1]

That transport question became the central theme of the KPV literature. The primary papers are about how the tripeptide enters intestinal cells and what happens to inflammatory signalling inside those cells and in mouse models of colitis once it does.

The primary studies, and what each measured#

Dalmasso et al., Gastroenterology, 2008#

This study examined whether KPV is carried into intestinal epithelial cells by PepT1, a transporter that moves small di- and tripeptides across the gut lining. In cultured human intestinal cell lines, the authors reported PepT1-dependent uptake of KPV and a reduction in NF-κB and MAP-kinase signalling and in inflammatory cytokine secretion after exposure. In two mouse colitis models (DSS- and TNBS-induced), mice that received KPV showed reduced markers of inflammation compared with controls. The experiments were in cells and mice; no people were involved.^[1]

Kannengiesser et al., Inflammatory Bowel Diseases, 2008#

Published the same year by a separate group, this paper looked at KPV in murine models of inflammatory bowel disease (DSS colitis and a T-cell transfer model) and in cell culture. It reported a reduction in inflammatory readouts and examined whether the effect depended on the melanocortin-1 receptor that full-length α-MSH uses, concluding that at least part of KPV's activity appeared independent of that receptor.^[2]

Laroui et al., Gastroenterology, 2010#

This is a drug-delivery paper rather than a pharmacology paper. The same Emory group that published the 2008 PepT1 work loaded KPV into polylactic-acid nanoparticles, encapsulated them in a polysaccharide hydrogel designed to release in the colon, and compared the result with free KPV in a mouse colitis model. The point of the study was that the targeted particles produced a comparable reduction in inflammatory markers at a far lower amount of peptide than free KPV, which is a statement about delivery efficiency, not a new claim about the peptide's biology.^[4]

What has not been studied#

The absence is as important as the presence. There are no published human trials of KPV. In its evaluation of KPV as a candidate bulk substance for pharmacy compounding, the FDA stated that it had identified no human exposure data for the peptide by any route and placed it in the category of substances that may present significant safety risks in compounding.^[5] The mouse colitis findings have not been tested in people, the long-term behaviour of the molecule in any species is undescribed, and the two 2008 papers remain the core of the literature nearly two decades later, which is itself a signal: a finding that attracted sustained interest would usually have generated replication and extension.

• No human pharmacokinetic, safety or efficacy data in the published literature.
• No regulatory approval anywhere.
• Mechanistic claims (NF-κB, MAPK, receptor independence) rest on in-vitro and mouse evidence.
• The delivery work (Laroui 2010) used a formulation that is not what research vendors sell.

Reading a KPV listing with this in mind#

A listing that describes KPV with words such as "anti-inflammatory peptide" is borrowing the language of the two 2008 mouse papers and applying it as if it were established. A listing that states the sequence, the form, the amount per vial, the lot number and where the lot's analytical report can be read is describing a reagent. The second kind is the one a laboratory can actually use, because identity and purity are what determine whether an experiment with the material means anything. Our guide to reading a Certificate of Analysis covers what the report should show; the COA library lists every Renuvia lot and its current testing status.