Joel S. Gordon

HAIR FOLLICLE GROWTH CONTROLS

Research in hair biology has embarked in the pursuit for molecules that control hair growth. Many molecules already have been associated with the controls of hair patterning, hair maturation, and hair cycling and differentiation. Knowing how these molecules work gives us the tools for understanding and treating patients with hair disorders.

Retinoids affect collagen synthesis through inhibition of ascorbate-induced lipid peroxidation in cultured human dermal fibroblasts☆

Ascorbate has been shown to stimulate collagen synthesis in cultured human dermal fibroblasts by increasing transcription of the collagen genes. In the present studies, ascorbate stimulates lipid peroxidation at concentrations similar to those necessary to affect collagen synthesis. Molecules which inhibit lipid peroxidation, such as propyl gallate, cobalt chloride, and alpha-naphthol, also inhibit collagen synthesis, suggesting a correlation between the two phenomena. Retinoic acid and some synthetic retinoids have previously been shown to inhibit collagen synthesis in cultured human dermal fibroblasts. In our studies two different retinoids, at similar concentrations, inhibit both ascorbate-stimulated lipid peroxidation and collagen synthesis. Since high concentrations of retinoids were required, the ability of retinoids to inhibit the oxidant effect of ascorbate, and not their receptor-mediated activity, may be responsible for their effect on collagen synthesis.

Regulation of collagen synthesis by ascorbic acid: Characterization of the role of ascorbate-stimulated lipid peroxidation

Recently, we have described the ability of traditional lipid peroxidation inhibitors to inhibit ascorbate-stimulated collagen synthesis. In order to characterize further this effect, we have tested the ability of known and potential inhibitors of lipid peroxidation for their effects on ascorbate-stimulated collagen synthesis and lipid peroxidation. In our experiments, mannitol, a water soluble antioxidant, had no effect on ascorbate-induced collagen synthesis nor on lipid peroxidation. However, alpha-tocopherol, which is a lipophilic antioxidant, inhibited both effects of ascorbate. Superoxide dismutase, catalase, and their polyethylene glycol conjugate forms did not inhibit the ascorbate-stimulated collagen synthesis or lipid peroxidation. In addition, no effect was seen with the oxygen radical scavengers isopropanol, ethanol, or dimethyl sulfoxide. Two iron chelators, o-phenanthroline and alpha,alpha-dipyridyl, both inhibited ascorbate-induced lipid peroxidation and collagen synthesis, consistent with the previously described iron-dependence of lipid peroxidation by ascorbate. These results support a correlation between collagen synthesis and lipid peroxidation and provide a theory for the mechanism of ascorbic acid regulation of collagen synthesis.

Modulation of collagen synthesis by growth factors : the role of ascorbate-stimulated lipid peroxidation

Ascorbic acid has been shown to stimulate collagen synthesis through induction of lipid peroxidation leading to increased transcription of the collagen genes. The mechanism by which lipid peroxidation stimulates collagen transcription is unknown; however, an alteration of cell membranes may affect the activity of serum growth factors leading to a change in gene expression. To test this hypothesis, we treated dermal fibroblasts with transforming growth factor-beta (TGF-beta), epidermal growth factor (EGF), interleukin-1 (IL-1), platelet-derived growth factor (PDGF), or fibroblast growth factor (FGF) in the presence of lipid peroxidation stimulating (200 microM) and nonstimulating (1 microM) concentrations of ascorbic acid. EGF and IL-1 had no effect on collagen synthesis at either concentration of ascorbic acid. FGF affected collagen synthesis only in the presence of 200 microM ascorbic acid, producing both a stimulation (0.4-2 ng/ml) and an inhibition (greater than 50 ng/ml). PDGF and TGF-beta stimulated collagen synthesis in the presence of both concentrations of ascorbic acid, with TGF-beta producing an 11-fold increase in collagen synthesis in the presence of ascorbate. This synergism produced by the combination of ascorbic acid and TGF-beta was inhibitable by the lipid peroxidation inhibitor, propyl gallate. These results indicate that regulation of collagen synthesis by ascorbic acid does not occur through altering the response to EGF or Il-1. Ascorbate has no effect on PDGF but the effects of TGF-beta and FGF on collagen synthesis appear to be sensitive to lipid peroxidation.

Regulation of Collagen Synthesis in Human Dermal Fibroblasts by the Sodium and Magnesium Salts of Ascorbyl-2-Phosphate

Ascorbic acid has been shown to stimulate collagen synthesis in dermal fibroblasts by increasing the rate of transcription of collagen genes. Experiments involving the use of ascorbic acid require daily supplementation due to the instability of the molecule in aqueous solutions. In order to provide a more stable alternative to ascorbic acid, two salts of ascorbyl-2-phosphate, having a greater chemical stability than ascorbic acid, were tested for their ability to stimulate collagen synthesis in monolayer fibroblast cultures. The concentration and time dependence of their activities were compared with ascorbic acid. The magnesium salt of ascorbyl-2-phosphate was found to be equivalent to ascorbic acid in stimulating collagen synthesis in these assays, while the sodium salt required at least a tenfold greater concentration to produce the same effect as ascorbic acid. Solutions of either ascorbic acid or the ascorbyl-2-phosphate analogs (at 10 mM) in phosphate-buffered saline (PBS) were relatively stable as shown by their decay rates and their ability to stimulate collagen synthesis even after nine days in solution prior to testing their effects on cultured cells. Ascorbic acid was unstable at neutral pH compared to solutions of either sodium or magnesium ascorbyl-2-phosphate. These data support the use of magnesium ascorbyl-2-phosphate in experiments where stability of ascorbic acid is a concern, e.g. in long-term cultures or in in vivo studies.

SIG1273: a new cosmetic functional ingredient to reduce blemishes and Propionibacterium acnes in acne prone skin.

Propionibacterium acnes is a major contributing factor to the inflammatory component of acne. The interaction of P. acnes with keratinocytes leads to an innate immune response via activation of toll‐like receptors (TLR2, TLR4) resulting in the production and secretion of pro‐inflammatory mediators. SIG1273, an isoprenylcysteine small molecule modulates inflammatory signaling pathways and kills P. acnes. SIG1273 represents a novel cosmetic functional ingredient that provides relief from blemishes in acne prone skin.

Anti-inflammatory and anti-bacterial properties of tetramethylhexadecenyl succinyl cysteine (TSC): a skin-protecting cosmetic functional ingredient

The skin is the first line of defence against exposure to microbial, physical, environmental and chemical insults. In mobilizing a protective response, several different cell types located in our skin release and respond to pro‐inflammatory cytokines ensuring skin homeostasis and health. However, chronic activation of this response eventually causes damage resulting in premature ageing. Diosodium tetramethylhexadecenyl succinyl cysteine (TSC or SIG1273), an isoprenylcysteine small molecule, down modulates these inflammatory signalling pathways in various cell types (keratinocytes, peripheral blood mononuclear cells (PBMCs) and endothelial cells) and possesses anti‐bacterial properties. Thus, TSC represents a novel cosmetic functional ingredient that provides a broad spectrum of benefits for the skin.

N-acetyl-S-farnesyl-l-cysteine suppresses chemokine production by human dermal microvascular endothelial cells.

Isoprenylcysteine (IPC) molecules modulate G‐protein‐coupled receptor signalling. The archetype of this class is N‐acetyl‐S‐farnesyl‐l‐cysteine (AFC). Topical application of AFC locally inhibits skin inflammation and elicitation of contact hypersensitivity in vivo. However, the mechanism of these anti‐inflammatory effects is not well understood. Dermal microvascular endothelial cells (ECs) are involved in inflammation, in part, by secreting cytokines that recruit inflammatory cells. We have previously shown that the sympathetic nerve cotransmitter adenosine‐5′‐triphosphate (ATP) and adenosine‐5′‐O‐(3‐thio) triphosphate (ATPγS), an ATP analogue that is resistant to hydrolysis, increase secretion of the chemokines CXCL8 (interleukin‐8), CCL2 (monocyte chemotactic protein‐1) and CXCL1 (growth‐regulated oncogene α) by dermal microvascular ECs. Production of these chemokines can also be induced by the exposure to the proinflammatory cytokine TNFα. We have now demonstrated that AFC dose‐dependently inhibits ATP‐, ATPγS‐ and TNFα‐induced production of CXCL1, CXCL8 and CCL2 by a human dermal microvascular EC line (HMEC‐1) in vitro under conditions that do not affect cell viability. Inhibition of ATPγS‐ or TNFα‐stimulated release of these chemokines was associated with reduced mRNA levels. N‐acetyl‐S‐geranyl‐l‐cysteine, an IPC analogue that is inactive in inhibiting G‐protein‐coupled signalling, had greatly reduced ability to suppress stimulated chemokine production. AFC may exert its anti‐inflammatory effects through the inhibition of chemokine production by stimulated ECs.

In vitro and clinical evaluation of SIG1273: a cosmetic functional ingredient with a broad spectrum of anti-aging and antioxidant activities

Isoprenylcysteine (IPC) small molecules were identified as a new class of anti‐inflammatory compounds over 20 years ago. Since then, they have been developed as novel cosmetic functional ingredients (CFI) and topical drug candidates. SIG1273 is a second generation CFI that has previously been shown to provide a broad spectrum of benefits for the skin through its anti‐inflammatory and antimicrobial properties.

SIG1459: A novel phytyl‐cysteine derived TLR2 modulator with in vitro and clinical anti‐acne activity

Cutibacterium (formerly Propionibacterium acnes) is a major contributor to the pathogenesis of acne. C. acnes initiates an innate immune response in keratinocytes via recognition and activation of toll‐like receptor‐2 (TLR2), a key step in comedogenesis. Tetramethyl‐hexadecenyl‐cysteine‐formylprolinate (SIG1459), a novel anti‐acne isoprenylcysteine (IPC) small molecule, is shown in this study to have direct antibacterial activity and inhibit TLR2 inflammatory signalling. In vitro antibacterial activity of SIG1459 against C. acnes was established demonstrating minimal inhibitory concentration (MIC = 8.5 μmol\L), minimal bactericidal concentration (MBC = 16.1 μmol\L) and minimal biofilm eradication concentration (MBEC = 12.5 μmol\L). To assess SIG1459s anti‐inflammatory activity, human keratinocytes were exposed to C. acnes and different TLR2 ligands (peptidoglycan, FSL‐1, Pam3CSK4) that induce pro‐inflammatory cytokine IL‐8 and IL‐1α production. Results demonstrate SIG1459 inhibits TLR2‐induced IL‐8 release from TLR2/TLR2 (IC50 = 0.086 μmol\L), TLR2/6 (IC50 = 0.209 μmol\L) and IL‐1α from TLR2/TLR2 (IC50 = 0.050 μmol\L). To assess the safety and in vivo anti‐acne activity of SIG1459, a vehicle controlled clinical study was conducted applying 1% SIG1459 topically (n = 35 subjects) in a head‐to‐head comparison against 3% BPO (n = 15 subjects). Utilizing the Investigator Global Assessment scale for acne as primary endpoint, results demonstrate 1% SIG1459 significantly outperformed 3% BPO over 8 weeks, resulting in 79% improvement as compared to 56% for BPO. Additionally, 1% SIG1459 was well tolerated. Thus, SIG1459 and phytyl IPC compounds represent a novel anti‐acne technology that provides a safe dual modulating benefit by killing C. acnes and reducing the inflammation it triggers via TLR2 signalling.