Traveling wave of inflammatory response to regulate the expansion or shrinkage of skin erythema

Disordered spatial pattern of redness signal on facial skin and visual perception of health, stress, and hidden aging

BACKGROUND

Well-being is commonly communicated across industries; however, experimental understanding how human perceive skin health and skin stresses are not sufficient.

MATERIALS AND METHODS

Image analysis algorithm, a* gradient, was developed to evaluate spatial pattern and shape of red signal on skin. Human perception for skin health and stresses were compared with technical measurements in two visual perception studies.

RESULTS

a* gradient correlated with perceived Inflamed Skin (R = 0.73, p < 0.01), Stressed Skin (R = 0.79, p < 0.01), Sensitive Skin (R = 0.75, p < 0.01), Healthy Skin (R = -0.83, p < 0.01), and Start Aging (R = 0.75, p < 0.01).

CONCLUSIONS

Disordered spatial pattern of redness signal drives human perception of skin health, stress, and aging. This new skin index of redness signal shows higher correlation with those human perception than basal a* mean, unevenness of a*, and other conventional skin color attributes.

Diffusive mediator feedbacks control the health-to-disease transition of skin inflammation

The spatiotemporal dynamics of inflammation provide vital insights into the understanding of skin inflammation. Skin inflammation primarily depends on the regulatory feedback between pro- and anti-inflammatory mediators. Healthy skin exhibits fading erythema. In contrast, diseased skin exhibits expanding erythema with diverse patterns, which are clinically classified into five types: circular, annular, arcuate, gyrate, and polycyclic. Inflammatory diseases with expanding erythema are speculated to result from the overproduction of pro-inflammatory mediators. However, the mechanism by which feedback selectively drives the transition from a healthy fading erythema to each of the five types of diseased expanding erythema remains unclear. This study theoretically elucidates the imbalanced production between pro- and anti-inflammatory mediators and prospective treatment strategies for each expanding pattern. Our literature survey showed that eleven diseases exhibit some of the five expanding erythema, thereby suggesting a common spatiotemporal regulation underlying different patterns and diseases. Accordingly, a reaction-diffusion model incorporating mediator feedback reproduced the five observed types of diseased expanding and healthy fading patterns. Importantly, the fading pattern transitioned to the arcuate, gyrate, and polycyclic patterns when the productions of anti-inflammatory and pro-inflammatory mediators were lower and higher, respectively than in the healthy condition. Further depletion of anti-inflammatory mediators caused a circular pattern, whereas further overproduction of pro-inflammatory mediators caused an annular pattern. Mechanistically, the bistability due to stabilization of the diseased state exhibits circular and annular patterns, whereas the excitability exhibits the gyrate, polycyclic, arcuate, and fading patterns as the threshold of pro-inflammatory mediator concentration relative to the healthy state increases. These dynamic regulations of diffusive mediator feedback provide effective treatment strategies for mediator production wherein skins recover from each expanding pattern toward a fading pattern. Thus, these strategies can estimate disease severity and risk based on erythema patterns, paving the way for developing noninvasive and personalized treatments for inflammatory skin diseases.

Microneedling with a Novel, n-3-PUFA-Rich Formulation Accelerates Inflammation Resolution to Improve Skin Recovery Outcomes in Adults with Healthy Skin

INTRODUCTION

Microneedling is a cosmetic procedure that leverages the skin's natural ability to heal in order to promote collagen formation and skin rejuvenation. To provide improved results, the technique can be combined with topical formulations. A new formulation of multiple actives, including omega-3 (n-3) polyunsaturated fatty acids (PUFAs), was designed to accelerate the resolution of inflammation and wound healing following micro-injury treatments, while enhancing the visible appearance of procedure results, including erythema, luminosity and skin texture.

METHODS

In this randomised, controlled, split-face study, we examined 32 healthy female participants aged 30-70 years for 4 weeks following microneedling treatment with a novel multiple-active-ingredient formulation or conventional microneedling protocol with a hyaluronic acid control serum. Changes in skin condition were assessed by blinded clinical photography and expert evaluation. Measurements were collected at baseline, 1 h, 1 day, 7 days and 28 days post treatment.

RESULTS

Significantly greater improvements in expert-assessed erythema, luminosity and skin texture were reported following application of the novel multiple-active-ingredient formulation than the hyaluronic acid control serum. This was confirmed by representative VISIA®-CR imaging.

CONCLUSION

These data provide new evidence for the role of a novel multiple-active-ingredient formulation for improving skin outcomes up to 28 days following microneedling in adults with healthy skin when compared with a hyaluronic acid serum. The n-3 PUFA content of this formulation may drive accelerated inflammation resolution and wound healing alongside the complementary action of the other active ingredients, leading to the observed improvements in erythema, luminosity and skin texture.

Inflammation propagation modeled as a reaction-diffusion wave

Inflammation is a physiological process aimed to protect the organism in various diseases and injuries. This work presents a generic inflammation model based on the reaction-diffusion equations for the concentrations of uninflamed cells, inflamed cells, immune cells and the inflammatory cytokines. The analysis of the model shows the existence of three different regimes of inflammation progression depending on the value of a parameter R called the inflammation number. If R>1, then inflammation propagates in cell culture or tissue as a reaction-diffusion wave due to diffusion of inflammatory cytokines produced by inflamed cells. If 0 Collapse

Key Words

• Cytokine storm
• Inflammation
• Inflammation propagation
• Reaction–diffusion equations
• Wave speed

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MESH Headings

• Inflammation/immunology
• Humans
• Cytokines/metabolism
• Cytokines/immunology
• Models, Biological
• Animals

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Affiliation(s)

W El Hajj Institut Camille Jordan, UMR 5208 CNRS, University Lyon 1, 69622 Villeurbanne, France
N El Khatib Department of Computer Science and Mathematics, Lebanese American University, P.O. Box 36, Byblos, Lebanon.
V Volpert Institut Camille Jordan, UMR 5208 CNRS, University Lyon 1, 69622 Villeurbanne, France; Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya St, Moscow 117198, Russian Federation

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