A significant component of human and animal innate immunity is composed of antimicrobial peptides and their precursor compounds. Phylogenetic analysis has been performed on a large number of species by comparing the underlying genes. Phenotypically, an ever-increasing number of antimicrobial peptides’ effects on the innate immune system have been identified. Antimicrobial peptides in mammals are still poorly understood biophysically. Especially frustrating is the fact that understanding their immunomodulatory activities would be significantly enhanced by knowing their structural characteristics.
This article will focus on LL-37, the only antimicrobial peptide produced from cathelicidin identified in humans. This amphipathic, helical peptide comprises 37 residues and is distributed throughout the body. In epithelial cells of the testis, skin, gastrointestinal tract, and respiratory system, as well as monocytes, neutrophils, T-cells, NK cells, and B-cells, it is expressed. Aside from controlling inflammation, it also attracts cells of the adaptive immune system to infection sites, neutralizes LPS, and promotes wound healing and re-epithelialization.
LL-37 and tissue healing
Antimicrobial and antibacterial properties apart, LL37 also plays a key function in the balance of pro-and anti-inflammatory chemicals in the human body. There is a precise balance to be struck between inflammation and tissue healing. To combat infections, the body must activate inflammatory reactions. But if left unaddressed, these same inflammatory reactions can obstruct recovery, encourage the creation of scar tissue and even contribute to autoimmune disorders. At least in part, LL-37’s actions on macrophages appear to play a role in balancing inflammation with healing.
When foreign infections are identified, macrophages cause inflammation. A pathogen is detected, and a signal is sent to the body’s immune system that a defense is required. Macrophages provide a new set of signals that reduce inflammation so that the body can progress to the next phase of healing once infections are defeated by the immune system. Macrophage activation can be reversed by peptides like LL-37. This substance changes anti-inflammation macrophages into pro-inflammatory macrophages when it is present in the body.
In macrophages, LL-37 production is increased by vitamin D secreted from the skin. At sites of inflammation and wounds, LL-37 plays a crucial function in the first-line defense against infection and systemic invasion of microorganisms. Bacterial and normal cells are both poisoned by it, and it is extremely resistant to proteolytic breakdown.
Studies have shown that LL-37 is a successful treatment for specific cancer cell types, according to a number of publications. Through the stimulation of bone morphogenetic protein (BMP) signaling, LL-37 suppresses gastric cancer cell proliferation. It was discovered; however, that overexpression of LL-37 promoted ovarian, lung, and breast cancer.
Benefits of LL-37 peptide
- Antimicrobial efficacy against bacteria, enveloped viruses, and fungi on a broad range
- Promotes the healing of wounds
- Defends against infection and reduces tissue inflammation
- Inhibits the growth of biofilm
LL37 is a host defense peptide that has many functions. Additionally, it promotes many cell responses, either directly or through the regulation of cell responses to antimicrobial chemicals and other immune mediators, in addition to its antimicrobial and antibiofilm activities. These peptides break membranes and offer broad-spectrum protection against localized bacterial invasion. That being said, if you are a researcher working in the lab, you can buy LL-37 online and further research its specific and valuable traits.