Last Tuesday, in Part 1, we explored two intriguing growth factors, EGF and FGF, which are gaining popularity in skincare due to their ability to stimulate cell signaling and induce the body's collagen and elastin production (among other things). Today, we shift our focus to discuss a few fascinating peptides. Similar to the growth factors, we won't be able to cover all the topical peptides in this single article.
In the previous article, we discussed the skin's anatomy and its cells, both in the epidermis and dermis. However, to quickly recap, the epidermis, the outermost layer, primarily comprises keratinocytes and can be divided into five sublayers.
Skin Anatomy Recap
The outermost layer, the stratum corneum, consists of flattened, dead keratinocytes that undergo cornification, migrating from deeper sublayers to form the skin's protective lipid barrier.
Moving through the epidermal layers, we encounter the stratum lucidum, mainly found in thick skin areas, followed by the stratum granulosum, where keratinocytes do much of their keratin production.
Deeper within the epidermis lies the stratum spinosum, housing those keratinocytes as well as Langerhans cells, which are part of the immune defense system.
Then, the innermost sublayer, the stratum basale, contains basal keratinocytes (stem cells), melanocytes responsible for skin color, and Merkel cells, enabling the sensation of light touch.
Now, let's briefly discuss the dermis beneath the epidermis, comprising two sub-layers: the papillary dermis with thin collagen and elastin fibers and the reticular dermis with thicker fibers. Fibroblasts, the main cells here, produce collagen and elastin, crucial for skin structure and elasticity. Additionally, the dermis houses sebaceous glands, sweat glands, hair follicles, and mast cells.
This serves as a quick summary of our previous discussion on skin anatomy and function. With that foundation, let's get into these topical peptides and their roles.
Topical Cosmetic Peptides:
Our first peptide is Palmitoyl tripeptide-1. When applied topically, it stimulates collagen production by first reaching the dermis, where collagen-producing fibroblasts reside. This peptide binds to fibroblast receptors, triggering intracellular signaling that boosts collagen production, enhancing skin firmness and strength.
Moving on to Palmitoyl tetrapeptide-7, it reduces inflammation, particularly after UVB exposure. By inhibiting the production of pro-inflammatory cytokines like IL-6, it calms irritated skin.
Palmitoyl tripeptide-8, our third peptide, soothes irritated skin, reduces inflammatory cytokines like IL-8, and may be beneficial for those with sensitive skin or rosacea.
Now, let's discuss Palmitoyl tetrapeptide-38, often referred to as matrixyl 6000 or matrixyl synthe-6 (note that the combination of palmitoyl tripeptide-1 and palmitoyl tetrapeptide-7 is referred to as matrixyl 3000). It stimulates the synthesis of six major components of the skin matrix, promoting greater collagen production and structural support in the epidermis (when compared to its earlier counterpart, matrixyl 3000).
Moving on, we transition to neurotransmitter-inhibiting peptides, targeting fine lines and wrinkles caused by muscle contractions. These peptides inhibit neurotransmitters like acetylcholine, promoting muscle relaxation and reducing the appearance of dynamic wrinkles and expression lines (i.e. crow's feet).
Our first peptide in this category is Acetyl Hexapeptide-8, mimicking Botox and proving safer and still extremely effective in reducing wrinkles as a result of inhibiting muscle contractions.
Another peptide, acetyl octapeptide-3, compares favorably with Acetyl Hexapeptide-8 in reducing wrinkle depth, and it is also considered a "botox in a bottle" alternative.
There are more topical peptides to explore, such as those for eyelash and nail growth, addressing under-eye bags and dark circles. I'll cover these in a future article and share my formulations on my social accounts as well!
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