Creative Touch Permanent Makeup and Aesthetics

Collagen provides the skin’s tensile scaffolding, but its clinical value lies in its structural organisation rather than simple quantity. Our focus is the balance between synthesis and MMP-driven degradation, specifically managing the Type I:III ratio which shifts during perimenopause. To achieve durable results, we must resolve the “maturation bottleneck”, ensuring that procollagen is successfully hydroxylated and cross-linked into functional fibrils rather than being degraded intracellularly.

Collagen is the most abundant protein in the human body and the primary structural component of the dermis, forming the fibrillar scaffold that gives skin its tensile strength, firmness, and capacity for resilience. In skin, the total collagen content decreases by approximately 1% per year from early adulthood, a decline that accelerates significantly with UV exposure, hormonal transition, and chronic stress. What makes this decline clinically interesting is that it does not operate through a single mechanism: reduced synthesis, increased enzymatic degradation, and impaired procollagen maturation are three independently occurring processes that can compound independently of each other. Understanding which is dominant in a given client determines which approach to collagen support is most relevant.

The Collagen Types in Skin

Human skin contains numerous collagen types, but two dominate the dermis. Collagen Type I comprises approximately 70% of the skin’s dry weight and provides the primary tensile strength. Collagen Type III makes up 8–11%, contributing elasticity and the capacity for tissue responsiveness. The adult skin maintains a Type I:III ratio of approximately 4:1, compared to the 1:1 ratio found in foetal and actively healing skin. This ratio is not simply a compositional detail: research on hybrid I/III collagen fibrils has shown that fibrils containing both types are significantly more effective at activating fibroblasts, stimulating cell polarisation, and driving new collagen synthesis than fibrils composed of either type alone. The ratio between these two collagens therefore feeds back into the capacity for collagen production – a lower Type III proportion progressively reduces the signalling that drives fibroblast activity. ^[2]

Collagen Type VII forms the anchoring fibrils that connect the basement membrane to the underlying dermis, maintaining the structural integrity of the dermo-epidermal junction. Its loss is particularly relevant in fragile, thinning, or photo-damaged skin where the junction’s mechanical stability is compromised. These less-discussed collagen types are where the conversation between barrier repair, skin thinning, and professional treatment effects becomes structurally precise. ^[5]

How Collagen Is Made

Collagen synthesis is a multi-step intracellular and extracellular process, each stage of which can independently become a limiting factor.

Fibroblasts transcribe procollagen mRNA, with TGF-β1 being the primary growth factor signal that drives procollagen gene expression. TGF-β1 signals through SMAD2 and SMAD3 transcription factors, which translocate to the nucleus and directly activate the COL1A1 and COL1A2 promoters driving Type I procollagen chain transcription – the same SMAD pathway that polynucleotides activate through the macrophage-mediated A2AR route, reaching fibroblast procollagen transcription through a paracrine mechanism when direct TGF-β responsiveness is reduced by senescence. Procollagen chains are then hydroxylated intracellularly: prolyl 4-hydroxylase and lysyl hydroxylase modify specific proline and lysine residues, a process that requires vitamin C as an obligate cofactor for enzyme activity. Without adequate hydroxylation, procollagen chains fail to form the stable triple helix structure and are instead degraded intracellularly before secretion. Vitamin C depletion does not simply reduce collagen synthesis speed; it produces structurally defective collagen that is degraded before it contributes to the extracellular matrix at all. Beyond its cofactor role, ascorbic acid also directly stimulates procollagen mRNA expression in fibroblasts, making it active at two independent points in the synthesis pathway. ^[1]

Once secreted, procollagen is cleaved to tropocollagen by specific extracellular proteinases – ADAMTS-2 and ADAMTS-3 remove the N-terminal propeptide; BMP-1 and tolloid-family enzymes cleave the C-terminal propeptide – yielding mature tropocollagen that self-assembles into fibrils. The cleaved propeptides do not simply disperse: the C-propeptide circulates systemically and acts as an autoregulatory feedback inhibitor of further procollagen synthesis in fibroblasts, providing a self-limiting mechanism that prevents runaway collagen overproduction under sustained TGF-β drive. Clinically, circulating procollagen C-propeptide (PICP) is a usable biomarker of fibroblast synthetic activity – and the feedback mechanism is a useful counterpoint to the assumption that maximal TGF-β stimulation produces maximal collagen output.

Cross-linking is catalysed by lysyl oxidase (LOX), a copper-dependent amine oxidase secreted by fibroblasts into the extracellular space, where it drives the oxidative deamination of lysine and hydroxylysine residues on adjacent tropocollagen molecules – generating the covalent aldehyde crosslinks that lock mature fibrils into mechanically stable structures. LOX activity is absolutely dependent on dietary copper, and deficiency produces connective tissue fragility equivalent to impaired cross-linking by any other mechanism. LOX is additionally suppressed by elevated homocysteine – the amino acid that accumulates with insufficient B12, B6, or folate – providing a specific nutritional pathway to impaired collagen maturation entirely independent of the synthesis and hydroxylation steps. This extracellular maturation step is the one most often overlooked in conversations about collagen support – a treatment that increases procollagen synthesis but does not support the maturation and cross-linking steps produces less functional extracellular collagen than the gene expression data alone would suggest.

Why Collagen Declines

Chronological Ageing

Fibroblasts produce less TGF-β1 over time, progressively reducing the signal for procollagen transcription. Alongside this, MMP activity increases with age independently of UV exposure, meaning basal collagen turnover gradually shifts toward net loss. The Type I:III ratio typically shifts toward higher Type I dominance as Type III production is disproportionately reduced, further impairing the fibroblast activation feedback loop described above. ^[1]

UV Radiation

UV exposure operates through two parallel mechanisms. A single minimal erythema dose (2 MED) produces near-complete suppression of procollagen synthesis that persists for 24 hours, mediated by TGF-β pathway impairment. Simultaneously, UV exposure activates AP-1 transcription through reactive oxygen species, which drives MMP-1, MMP-3, and MMP-9 upregulation. MMP-1 cleaves fibrillar collagen Types I and III at a single site within the triple helix; MMP-3 and MMP-9 then degrade the cleaved fragments. Chronic UV exposure therefore creates compounding fragmented collagen accumulation alongside progressive synthesis suppression. Which is why photoaged skin feels and behaves structurally differently from intrinsically aged skin of equivalent chronological age. ^[9]

Hormonal Transition

The perimenopause mechanism is more nuanced than the commonly cited statistic of “30% collagen loss in five years” suggests. Primary fibroblast research using in vitro menopausal hormone conditions produced a counterintuitive finding: procollagen gene expression actually increased under menopausal conditions in the short term, representing a compensatory fibroblast response. However, this increased synthesis was insufficient to prevent net collagen loss because of simultaneous upregulation of MMP-1 and MMP-3 activity, and because of impaired procollagen protein maturation downstream of the transcription stage. The problem in menopausal skin is not primarily that fibroblasts stop trying to make collagen; it is that the degradation and maturation environment changes such that what they make is increasingly lost before contributing to the structural matrix. ^[10]

This distinction is clinically important. Treatments that increase procollagen mRNA expression alone are working on a step that is already being compensated for. Approaches that simultaneously reduce MMP activity, support the maturation pathway, and restore the Type III/Type I balance are more comprehensively addressing what is actually failing.

For clients where fibroblast senescence is the prominent limiting factor – where the fibroblast population has genuinely reduced capacity rather than simply reduced stimulation – PLLA addresses this at a more fundamental level than treatments that provide a synthesis signal alone. Its direct PI3K/AKT activation suppresses the p53/p21 senescence axis in fibroblasts, partially restoring their synthetic capacity rather than asking cells with diminished function to perform more. ^[7] For the post-menopausal presentation where previous stimulation treatments have underdelivered, this mechanism distinction is worth considering in treatment planning.

Chronic Stress

Cortisol reduces fibroblast activity and impairs TGF-β1 signalling directly, suppressing both procollagen transcription and the growth factor environment that sustains fibroblast viability. The same HPA axis elevation that suppresses cholesterol and ceramide synthesis in the stratum corneum is simultaneously reducing the dermal collagen production rate. Stress-related skin changes operate at both the epidermal barrier and the dermal structural layers concurrently.

Vitamin C: Two Mechanisms, One Priority

Given collagen synthesis’s absolute dependency on vitamin C at the hydroxylation step, and vitamin C’s direct stimulation of procollagen mRNA independently of that cofactor role, it occupies a unique position among topical actives. Topical vitamin C at stable, bioavailable concentrations reaches the dermis sufficiently to support both functions. It also reduces the ROS-driven AP-1 signalling that upregulates MMPs, giving it a simultaneous synthesis-supporting and degradation-reducing action. For clients whose collagen support strategy includes a single topical active alongside professional treatments, vitamin C addresses the mechanism more completely than any other cosmeceutical. ^[8]

Retinoids and Collagen Remodelling

Retinoids support collagen production through a complementary but distinct mechanism: they upregulate TGF-β1 and reduce MMP expression, working on the growth factor signalling environment rather than the synthesis machinery directly. Long-term retinoid use consistently increases measurable dermal collagen density and improves the Type I:III ratio by supporting the fibroblast activation environment. The combination of retinoids and vitamin C addresses the TGF-β/MMP regulatory level and the procollagen hydroxylation/maturation level simultaneously, which is why this pairing is so consistently effective in collagen-focused homecare protocols.