KPV is a very short peptide — just three amino acids: lysine, proline and valine (the abbreviation comes from their one-letter symbols). It was not invented from scratch in a laboratory: it is the “tail end” of alpha-MSH, a natural hormone the body makes itself. Since the late 1980s it has been studied as a fragment that keeps the anti-inflammatory action of the whole hormone but does not darken the skin. In this review we explain in plain terms what KPV is, how it is meant to work and how strong the evidence is. And that evidence — it has to be said upfront — comes exclusively from cell and mouse studies; there is no published study in which KPV was given to people.
What KPV is
Alpha-MSH is a hormone built from 13 amino acids, known mainly for stimulating pigment production in the skin. It has a second face, though: it suppresses fever and inflammation. In 1989 Hiltz and Lipton tested whether that second function lies in the very end of the molecule — the last three amino acids (positions 11–13), which is KPV. In mice whose ears had been made to swell with an irritant, KPV inhibited the swelling more strongly the higher the dose. The authors concluded that this small fragment may have “general anti-inflammatory activity”. The 2008 review by Brzoska and colleagues sums up this line of research: KPV preserves the anti-inflammatory effect of alpha-MSH but lacks its pigmentary action — which is why it was singled out as an alternative to the whole hormone.
How it works — the NF-κB “switch” and the PepT1 transporter
Inside immune cells and gut cells there is a “master switch” for inflammation, a protein called NF-κB. When it is switched on, the cell starts producing inflammatory signals (cytokines). Dalmasso and colleagues (2008) showed on human intestinal and lymphocyte cell lines that KPV at nanomolar concentrations — that is, very low ones — inhibited the activation of NF-κB and of a related pathway (MAP kinases) and reduced the secretion of inflammatory cytokines. They also discovered how KPV gets into the cell: through the PepT1 transporter, a “gate” in the cell membrane that normally pulls short peptides from food inside. PepT1 is found mainly in the small intestine, but during inflammation of the large intestine its amount rises. It is an intriguing mechanism: an inflamed gut has more gates through which KPV can enter.
Importantly, KPV seems to act differently from the whole hormone. Getting and colleagues (2003) compared it with alpha-MSH in a mouse model of peritonitis. KPV reduced the influx of inflammatory cells, but its action was not blocked by a melanocortin-receptor antagonist, it did not raise intracellular cAMP (the typical signal of those receptors) and it also worked in mice with a non-functional MC1 receptor. The authors' conclusion: KPV is “unlikely to mediate its effects through melanocortin receptors” and more likely acts by inhibiting the functions of interleukin-1β. Kannengiesser and colleagues (2008) reached a similar conclusion in colitis — the effect was “at least partially independent” of the MC1 receptor.
Structure and origin
KPV is a tripeptide, a chain of three amino acids: lysine–proline–valine. It is a natural fragment (alpha-MSH is produced in the body from a larger precursor protein), but research uses a synthetic version. The authors of the 2008 review stress that the simple structure means easy and cheap production; they also describe a related tripeptide, KdPT, corresponding to a fragment of interleukin-1β, studied for the same purpose.
What was studied — cells and animals
Colitis (mice). This is the best-documented direction. Dalmasso and colleagues (2008) gave KPV in drinking water to mice with colitis induced by two different methods (DSS and TNBS); KPV reduced the incidence of colitis and the expression of pro-inflammatory cytokines. Kannengiesser and colleagues (2008) used two other models: in DSS colitis the treated mice recovered earlier and regained body weight more clearly, and the gut tissue showed fewer inflammatory infiltrates and lower myeloperoxidase activity (an enzyme of inflammatory cells); in so-called transfer colitis (induced by transplanting lymphocytes) KPV also led to recovery. In mice with a non-functional MC1 receptor, KPV rescued all animals in the treatment group from death during colitis. Viennois and colleagues (2016) added the missing piece of the puzzle: in mice lacking the PepT1 transporter, KPV did not prevent colitis-associated tumour formation, although in ordinary mice it did. In other words: no PepT1 gate, no effect. PepT1 was markedly increased in human colorectal tumour biopsies — but that is an observation of tissue, not a study of giving KPV to people.
Other inflammation models. Getting and colleagues (2003) demonstrated KPV activity in mouse peritonitis induced by crystals and by interleukin-1β. Schaible and colleagues (2013) gave mice a single dose of KPV (1 mg/kg intraperitoneally) 30 minutes after experimental brain injury: the area of secondary damage was considerably smaller, microglia (the brain's immune cells) were less activated, and fewer neurons died by apoptosis. Interestingly, the levels of the cytokines TNF-α and IL-1β did not fall — so the effect was not a simple “switching off” of inflammation.
Microbes (in vitro). Cutuli and colleagues (2000) tested alpha-MSH and KPV against two typical pathogens: Staphylococcus aureus and the yeast Candida albicans. The peptides inhibited colony formation by the staphylococcus and reduced the viability of the yeast across a broad range of concentrations, including very low (picomolar) ones, and did not weaken the killing of microbes by human neutrophils — if anything, they enhanced it. This was a test-tube study, not a study in people.
Skin. The first experiment from 1989 concerned the skin (ear swelling), and the 2008 review lists inflammatory skin diseases as a potential application of the tripeptides. We found no study, however, in which KPV was given to people with a skin condition.
No human studies — what that means
We searched PubMed for the names “KPV”, “Lys-Pro-Val” and “alpha-MSH 11-13” combined with terms denoting clinical studies, and the ClinicalTrials.gov registry. The result: zero studies in which KPV was administered to humans — neither healthy volunteers nor patients. The only “human” data are experiments on human cells in the laboratory (intestinal cell lines, lymphocytes, neutrophils) and the PepT1 observation in tumour biopsies mentioned above. KPV is not an approved medicine in any country. So it is unknown whether it is absorbed from the human gut in any meaningful amount, how long it acts, whether it is safe with prolonged use, or whether it affects the course of any disease at all. Many substances that worked in mouse colitis models failed in patients.
Safety and the limits of the evidence
All efficacy data come from cells and rodents. It is worth noting that different studies gave KPV by different routes — orally in drinking water (Dalmasso 2008) or intraperitoneally (Getting 2003, Schaible 2013) — and an effect was seen with each. No study compared these routes head to head, so the view that the oral route is “better” for the gut because it exploits the PepT1 transporter remains a hypothesis derived from mechanism, not a verified fact. Not every inflammatory readout responded to KPV: in Getting's work it did not inhibit cytokine release by macrophages, and in the brain-injury model it did not lower TNF-α or IL-1β. In theory a substance that inhibits NF-κB could weaken innate immunity during infection; Cutuli's data point instead to antimicrobial action, but only in vitro. Nothing is known about safety in humans. We deliberately give no methods of use and no doses.
The wider context — melanocortins
KPV belongs to the world of melanocortins — a family of peptides derived from alpha-MSH and related hormones. Other compounds from this family described in our knowledge base act the opposite way to KPV, precisely through melanocortin receptors: melanotan II (skin pigmentation) and PT-141, or bremelanotide (sexual function). KPV is interesting precisely because it was studied as the fragment “without the tan” — with the anti-inflammatory action preserved and no effect on pigment. Like another tripeptide from the encyclopaedia, glutathione, it shows that even three amino acids can have their own distinct biology.
Summary
KPV is the last three amino acids of the hormone alpha-MSH. In cell studies it inhibits the inflammatory “switch” NF-κB at nanomolar concentrations and enters cells through the PepT1 transporter, of which there is more in an inflamed gut. In mice it eased colitis in several independent models, reduced brain damage after injury and, in the test tube, inhibited staphylococcus and Candida. It appears to act differently from the whole hormone — probably not via melanocortin receptors. At the same time no study involving humans exists, so the efficacy and safety of KPV in people remain unknown, and everything known about it is preclinical.
Sources
- Brzoska T, Luger TA, Maaser C, Abels C, Böhm M. Alpha-melanocyte-stimulating hormone and related tripeptides: biochemistry, antiinflammatory and protective effects in vitro and in vivo, and future perspectives for the treatment of immune-mediated inflammatory diseases. Endocrine Reviews. 2008;29(5):581–602. PMID: 18612139. DOI: 10.1210/er.2007-0027. pubmed.ncbi.nlm.nih.gov/18612139
- Dalmasso G, Charrier-Hisamuddin L, Nguyen HT, Yan Y, Sitaraman S, Merlin D. PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation. Gastroenterology. 2008;134(1):166–178. PMID: 18061177. DOI: 10.1053/j.gastro.2007.10.026. pubmed.ncbi.nlm.nih.gov/18061177
- Kannengiesser K, Maaser C, Heidemann J, Luegering A, Ross M, Brzoska T, Bohm M, Luger TA, Domschke W, Kucharzik T. Melanocortin-derived tripeptide KPV has anti-inflammatory potential in murine models of inflammatory bowel disease. Inflammatory Bowel Diseases. 2008;14(3):324–331. PMID: 18092346. DOI: 10.1002/ibd.20334. pubmed.ncbi.nlm.nih.gov/18092346
- Viennois E, Ingersoll SA, Ayyadurai S, Zhao Y, Wang L, Zhang M, Han MK, Garg P, Xiao B, Merlin D. Critical role of PepT1 in promoting colitis-associated cancer and therapeutic benefits of the anti-inflammatory PepT1-mediated tripeptide KPV in a murine model. Cellular and Molecular Gastroenterology and Hepatology. 2016;2(3):340–357. PMID: 27458604. DOI: 10.1016/j.jcmgh.2016.01.006. pubmed.ncbi.nlm.nih.gov/27458604
- Hiltz ME, Lipton JM. Antiinflammatory activity of a COOH-terminal fragment of the neuropeptide alpha-MSH. FASEB Journal. 1989;3(11):2282–2284. PMID: 2550304. pubmed.ncbi.nlm.nih.gov/2550304
- Getting SJ, Schiöth HB, Perretti M. Dissection of the anti-inflammatory effect of the core and C-terminal (KPV) alpha-melanocyte-stimulating hormone peptides. Journal of Pharmacology and Experimental Therapeutics. 2003;306(2):631–637. PMID: 12750433. DOI: 10.1124/jpet.103.051623. pubmed.ncbi.nlm.nih.gov/12750433
- Cutuli M, Cristiani S, Lipton JM, Catania A. Antimicrobial effects of alpha-MSH peptides. Journal of Leukocyte Biology. 2000;67(2):233–239. PMID: 10670585. DOI: 10.1002/jlb.67.2.233. pubmed.ncbi.nlm.nih.gov/10670585
- Schaible EV, Steinsträßer A, Jahn-Eimermacher A, Luh C, Sebastiani A, Kornes F, Pieter D, Schäfer MK, Engelhard K, Thal SC. Single administration of tripeptide α-MSH(11-13) attenuates brain damage by reduced inflammation and apoptosis after experimental traumatic brain injury in mice. PLoS One. 2013;8(8):e71056. PMID: 23940690. DOI: 10.1371/journal.pone.0071056. pubmed.ncbi.nlm.nih.gov/23940690
For in-vitro laboratory research only. It is not a human medicine and is not for treatment.