Metalloproteinases MMP
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Matrix metalloproteinases, abbreviated as MMP from the English name matrix metalloproteinases, are a family of zinc-dependent proteolytic enzymes involved in controlled tissue remodeling. In the skin, they degrade extracellular matrix components, including collagen, proteoglycans, fibronectin, and elements of elastic fibers. Their activity is essential during wound healing, angiogenesis, the immune response, and physiological skin renewal. A problem arises when the synthesis or activation of MMPs exceeds the body's ability to inhibit them through tissue inhibitors of metalloproteinases, or TIMP. A chronic predominance of degradation processes leads to collagen fragmentation, disruption of dermis organization, the formation of wrinkles, and loss of firmness. The strongest environmental activator of MMPs in the skin is ultraviolet radiation.
Metalloproteinases MMP - what are they
MMPs belong to the family of endopeptidases, which are enzymes that cleave peptide bonds within proteins. A zinc ion located in the catalytic center is essential for their activity. Most enzymes are produced as inactive prometalloproteinases, called pro-MMPs, and require activation through the proteolytic removal of a fragment blocking the enzymatic center. This mechanism protects tissues from uncontrolled degradation.
Over 20 MMPs have been identified in the human body. In the skin, the following are of particular importance:
Group | Most important enzymes | Main function in the skin |
|---|---|---|
Collagenases | MMP-1, MMP-8, MMP-13 | Cleavage of the triple helix of fibrillar collagens, especially types I and III |
Gelatinases | MMP-2, MMP-9 | Degradation of denatured collagen fragments, gelatin, and type IV collagen |
Stromelysins | MMP-3, MMP-10 | Breakdown of proteoglycans and fibronectin, as well as activation of other pro-MMPs |
Metalloelastase | MMP-12 | Elastin remodeling and involvement in the development of solar elastosis |
Membrane-type MMPs | including MMP-14 | Proteolysis on the cell surface and activation of MMP-2 |
MMPs are produced, among others, by fibroblasts, keratinocytes, endothelial cells, macrophages, and neutrophils. Their activity is controlled by four tissue inhibitors of metalloproteinases: TIMP-1, TIMP-2, TIMP-3, and TIMP-4. Thus, the state of the matrix is determined not by the concentration of MMPs alone, but by the balance between the synthesis, activation, and inhibition of enzymes and the production of new structural proteins.
Metalloproteinases are not merely "harmful aging enzymes." Physiological, time-limited MMP activity allows for the removal of damaged collagen and its replacement with a new matrix. What is primarily unfavorable is their chronic or excessive activation, disproportionate to collagen synthesis.
Metalloproteinases MMP - why they break down collagen
Fibrillar collagen has a stable triple helix structure, resistant to the action of most proteases. MMP collagenases have a structure that allows recognition of the fibril, local unwinding of the helix, and cleavage of the molecule at a specific site. In human skin, the most important initiating role is played by MMP-1.
The degradation process occurs in stages:
- MMP-1 recognizes type I or III collagen and cleaves each of the three strands of the helix.
- Fragments spanning approximately 3/4 and 1/4 of the original molecule's length are formed.
- The fragments lose their stable structure and partially undergo denaturation.
- MMP-2 and MMP-9, referred to as gelatinases, break them down into smaller peptides.
- The remnants are removed or subjected to further proteolysis.
In normal healing, such a mechanism prepares space for a new matrix. In skin chronically exposed to UV radiation, however, repeated degradation cycles occur. Fiber fragmentation reduces the mechanical tension of fibroblasts and disrupts their contact with the matrix. Cells adopt a more collapsed shape, produce less collagen, and generate more reactive oxygen species. A positive feedback loop is established: collagen fragmentation weakens fibroblasts, and weakened fibroblasts produce less new matrix and promote further MMP activation.
UV radiation also acts in a dual manner. It increases collagen degradation by MMPs while simultaneously impairing the TGF-β/Smad pathway, which is one of the main regulators of type I procollagen synthesis. Thus, the skin loses collagen both due to faster breakdown and slower reproduction. The clinical consequences are wrinkles, laxity, roughness, enlarged pores, and uneven skin texture.
Metalloproteinases MMP - what increases their activity
The best-documented activator of MMPs is UVA and UVB radiation. Photons absorbed by cellular chromophores increase the generation of reactive oxygen species, such as superoxide anion radical, hydrogen peroxide, and hydroxyl radical. Oxidative stress triggers MAPK kinases: ERK, JNK, and p38. This leads to the activation of transcription factors AP-1 and NF-κB, which increase the gene expression of MMP-1, MMP-3, MMP-9, and MMP-12.
The activity of metalloproteinases is also enhanced by:
- tobacco smoking, which increases oxidative stress and MMP-1 expression; UVA radiation and tobacco smoke can act additively;
- air pollution, especially particulate matter and polycyclic aromatic hydrocarbons, activating, among others, the AhR receptor;
- chronic inflammation, as interleukin 1β, TNF-α, and other inflammatory mediators stimulate the expression of multiple MMPs;
- cellular senescence, in which senescent cells secrete cytokines and proteases forming the pro-inflammatory SASP phenotype;
- excess reactive oxygen species generated in cellular metabolism, during uncompensated diseases, and under the influence of environmental factors;
- chronic hyperglycemia and glycation, which stiffen collagen, disrupt its normal turnover, and increase oxidative-inflammatory stress;
- recurrent skin barrier damage, irritation, and the uncontrolled use of aggressive procedures;
- postmenopausal estrogen deficiency, associated with a decrease in collagen synthesis and an altered balance in its metabolism.
An increase in MMPs may be transient and physiological. Controlled micro-injury during a medical procedure initially enhances the activity of enzymes needed to remove the damaged matrix, after which it triggers fibroblast proliferation and the synthesis of new collagen. Therefore, not every MMP activation should be equated with permanent skin damage.
Metalloproteinases MMP - how to limit their activity in the skin
The most important method of reducing chronic MMP activation is daily, broad-spectrum UVA/UVB photoprotection. It includes an adequate amount of sunscreen, reapplication during exposure, protective clothing, and avoiding intense sun exposure. Sunscreen does not reverse existing collagen fragmentation, but it limits further impulses leading to the activation of the ROS–MAPK–AP-1–MMP axis.
The following are also important:
- smoking cessation and reducing exposure to tobacco smoke;
- gentle skincare supporting the epidermal barrier;
- treatment of acne, inflammatory dermatoses, and other sources of chronic inflammation;
- proper glycemic control;
- a diet providing protein, vitamin C, zinc, and other components essential for matrix synthesis, without treating supplementation as a direct “MMP blocker”;
- the use of retinoids following appropriate qualification. Tretinoin is the best documented, reducing UV-induced MMP induction and supporting collagen synthesis. However, it can cause irritation, is not suitable for every patient, and requires caution during pregnancy.
Treatments available at Ambasada Urody that can serve to remodel skin with signs of photoaging and collagen loss include:
- fractional laser resurfacing: iPixel Er:YAG, Pixel CO₂, Palomar 2940, and Alma Hybrid fractional solutions; they create controlled zones of injury and initiate months-long matrix remodeling;
- non-ablative lasers, Palomar Deep IR, IPL photorejuvenation Alma DyeVL PRO and Icon Cynosure MaxG; they thermally affect the dermis or reduce components of photodamage;
- microneedle radiofrequency, including DeAge EX, as well as radiofrequency Accent Prime, Pellevé RF, and INDIBA Deep Care;
- HIFU SonoQueen and Zaffiro thermolifting, used for controlled tissue heating and stimulating collagen remodeling;
- Dermapen 4.0 microneedling, also in procedures with exosomes, and classic microneedle mesotherapy;
- PRP platelet-rich plasma, PRF fibrin, and CGF concentrates, providing autologous mediators of the repair process;
- tissue stimulators, including amino acid preparations, polynucleotides, Karisma, Profhilo, and Juvelook;
- needle mesotherapy, PRX-T33 and RetisesCT chemical peels, and PDO, PLLA, or PCL threads;
- supportive treatments, such as LPG endermologie, Icoone, cryoplasty, iontophoresis, LED light, and lifting massages.
These procedures are not simple MMP inhibitors. Their goal is the controlled initiation of healing and shifting the balance toward proper matrix reconstruction. The selection of technology, intensity, and intervals between treatments should result from skin examination, phototype, degree of photodamage, comorbidities, and the patient's regenerative capacity.
