Ultraviolet (UV) exposure accelerates skin aging through wavelength-dependent effects. Ultraviolet A (UVA) penetrates relatively deeply into the dermis and promotes oxidative stress and extracellular-matrix remodeling, whereas ultraviolet B (UVB) is absorbed predominantly in the epidermis and produces direct DNA damage and inflammation; nevertheless, UVB can also alter dermal fibroblast matrix metabolism in experimental models. The present study specifically used UVB irradiation (peak wavelength, 306 nm) to examine inflammatory collagen loss. UVB-induced cellular injury activates the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, leading to caspase-1-dependent maturation of interleukin-1β (IL-1β), activation of nuclear factor-κB (NF-κB), and matrix metalloproteinase (MMP)-associated collagen degradation. Pulsed electromagnetic field (PEMF) stimulation is a non-optical biophysical modality that may modulate inflammatory and matrix responses. Here, we characterized the effects of PEMF exposure using Corefacial on UVB-induced dermal collagen loss in association with the A2A adenosine receptor (A2AAR)/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway. In UVB-exposed fibroblasts, PEMF restored A2AAR and PKA protein levels, cAMP levels, and the pNLRP3/NLRP3 ratio, similar to the effects of the A2AAR agonist CGS-21680. PEMF also reduced apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), caspase-1 activation markers, IL-1β secretion, NF-κB nuclear translocation, and MMP2/MMP3/MMP9 expression and increased the levels of collagen I and collagen III. In the in vivo UVB model, PEMF similarly increased A2AAR and PKA protein levels, cAMP levels, and the pNLRP3/NLRP3 ratio, while attenuating IL-1β/NF-κB/MMP-associated responses and preserving dermal collagen. These findings are consistent with, but do not prove, involvement of A2AAR/cAMP/PKA-related signaling and inhibitory NLRP3 phosphorylation in the PEMF response. These results should be interpreted as evidence from a UVB-specific experimental model rather than a comprehensive model of solar photoaging.

Injectable collagen biomaterials are used to modify the dermal extracellular matrix in aged skin; however, whether concentration-dependent rheological differences are associated with distinct fibroblast responses remain unclear. We compared 3% and 6% atelocollagen (AtCOL) and examined three mechanobiological programs: (i) integrin (ITG) α5β1–ERK–cyclin D1 signaling related to proliferation; (ii) ITGβ1–FAK–YAP signaling related to matrix synthesis; and (iii) ITGα11β1/Tensin-1–positive fibrillar adhesion related to collagen assembly. Under the tested oscillatory shear conditions, 6% AtCOL displayed higher storage modulus (G′), loss modulus (G″), and complex viscosity, together with a lower tan δ, than 3% AtCOL. In aged mouse skin, the 6% formulation was associated with greater increases in ITGα5, pERK1/2, cyclin D1, PCNA, pFAK, nuclear YAP, COL1A1, COL3A1, ITGα11β1/Tensin-1 co-expression signal, collagen type I/III ratio, collagen type I fiber bundle width, mature collagen content, dermal collagen density, and an instrument-derived skin elasticity index, while MMP1, MMP2, and MMP9 were reduced. In an H₂O₂-induced fibroblast senescence model, ITGβ1 knockdown attenuated AtCOL-associated proliferative, matrix-synthetic, and fibrillar-adhesion responses. Complementary ITGβ1 overexpression produced directionally concordant increases in ITGA11 expression, relative fibroblast proliferation, COL1A1, and COL3A1 and decreases in MMP1, MMP2, and MMP9. Collectively, these findings are consistent with a concentration-dependent, ITGβ1-centered mechanotransduction model linking fibroblast proliferation, matrix synthesis, and collagen assembly within a single AtCOL system.

Facial retaining ligaments maintain soft-tissue position and support the lower face, but whether fractional subnanosecond Nd:YAG laser treatment can improve the matrix architecture of ultraviolet (UV)-aged ligament tissue remains unclear. We evaluated whether laser-associated matrix alteration was accompanied by coordinated changes in LATS1-YAP-IQGAP1-NFAT1 signaling and collagen type I-dominant remodeling. Male Sprague–Dawley rats were allocated to non-UV control, UV-aged, and UV-aged plus laser groups (n = 5 per group). After UV-aging induction, the laser group received a single fractional 1064 nm, 450 ps (subnanosecond) Nd:YAG treatment at 3.8 J/cm² and 10 Hz using a 6 × 6 mm spot, with a measured pulse energy of 1.07 J and a calculated irradiance of 8.44 GW/cm²; 30 stacks, corresponding to 30 laser shots delivered to the same target area, were applied over 3 s. UV exposure increased cytosolic pLATS1/LATS1, cytosolic pYAP, and ELISA-detected IQGAP1-associated pYAP signals while reducing nuclear YAP; laser treatment partially reversed these changes. Concurrently, laser treatment decreased ELISA-detected IQGAP1-associated pNFAT1 signals, restored nuclear NFAT1 localization, and reduced cytosolic pNFAT1. Quantitative immunofluorescence, histomorphometric, and ultrastructural analyses showed restoration of the collagen type I signal and collagen type I/III ratio and improvements in collagen density, coherency, angular deviation, and collagen bundle diameter. Laser treatment restored the expression of tendon/ligament-lineage markers, including scleraxis, mohawk homeobox, and tenomodulin; UV-induced elevations in osteogenic markers (RUNX2, SP7, and ALPL) were not significantly attenuated. Overall, fractional subnanosecond Nd:YAG laser treatment partially improved the matrix architecture of UV-aged rat facial retaining ligaments. These exploratory findings support an association model linking laser-associated matrix remodeling with coordinated changes in LATS1-YAP-IQGAP1-NFAT1 signaling, lineage-marker recovery, and collagen type I-dominant realignment, but do not establish a causal signaling sequence or functional mechanical strengthening.