bigrobbie
TID OG Member
- Sep 19, 2010
- 861
- 406
Efficacy of hexapeptide-7 on menopausal skin,
Timothy J. Falla, Lijuan Zhang, Journal of Drugs in Dermatology, (February 8, 2010)
Due to a reduction in estrogen levels peri-and post-menopausal skin exhibit a specific phenotype characterized by reduced thickness, reduced elasticity and increased dryness. Loss of these elements results in increased skin wrinkling and skin sagging. In addition, it is well documented that reduced estrogen levels also negatively impacts dermal wound healing. As a result we tested the hypothesis that molecules capable of stimulating and accelerating wound healing can supplement the skin's diminished activities produced by reduced estrogen. Heptapeptide-7, a fragment of a well-characterized wound healing peptide (HB- 107), was found to stimulate keratinocyte proliferation and migration and induce collagen synthesis. Microarray analysis of Heptapeptide-7-treated dermal keratinocytes revealed an up-regulation of cell division, growth factor and extracellular matrix genes. Validation of this approach was seen in a clinical study of 32 women (mean age 54) in which forehead wrinkles and skin texture were improved with the application of this peptide fragment.
HB-107, a nonbacteriostatic fragment of the antimicrobial peptide cecropin B, accelerates murine wound repair,
Phillip H.A. Lee, MD; Jennifer A. Rudisill, BA; Kenneth H. Lin, BA; Lijuan Zhang, PhD; Scott M. Harris, PhD; Timothy J. Falla, PhD; Richard L. Gallo, MD, PhD, Wound Repair and Regeneration Volume 12, Issue 3, Pages 351-358
Antimicrobial peptides are essential to innate host defense as effectors of pathogen clearance and can modify host cell behaviors to promote wound repair. While these two functions appear interrelated, it is unclear whether the ability to aid in wound repair requires inherent antimicrobial function. We hypothesized that the influence of antimicrobial peptides on wound repair is not dependent on antimicrobial function. To explore this, we analyzed the microbial killing activity of peptide fragments and correlated this with the ability to influence wound repair in mice. HB-107 [Hexapeptide 7] , a peptide lacking antimicrobial activity and originally derived from the antimicrobial cecropin B, showed up to 64 percent improvement in wound repair compared to scrambled peptide and vehicle controls, an effect comparable to treatment with recombinant human platelet-derived growth factor-BB (formulated as RegranexTM). Wounds treated with HB-107 showed keratinocyte hyperplasia and increased leukocyte infiltration. Furthermore, HB-107 stimulated interleukin-8 secretion from cultured endothelial cells, an effect that may explain the increase in leukocyte migration. These findings confirm that antimicrobial peptides can function as effectors of cutaneous wound repair. Moreover, this study furthers our understanding of antimicrobial peptides by showing that their wound repair properties can be independent of antimicrobial function.
Discussion
Antimicrobial peptides have been implicated as positive effectors of wound repair.2,4,18,19 In this study, we tested fragments of antimicrobial peptides for antimicrobial activity and correlated this with their ability to influence wound repair in mice. HB-107, a cationic peptide derived from the moth antimicrobial cecropin B,10 was found to aid in wound repair despite lacking antimicrobial activity. This ability to aid in wound repair was recapitulated in two different vehicles and shown to be comparable to the effect seen by the growth factor rhPDGF-BB, formulated as the commercial product RegranexTM. Further study of HB-107 suggested that it functions by stimulating keratinocyte proliferation and enhancing chemokine- induced leukocyte infiltration.
Normal wound repair involves a precise orchestration of inflammation, epithelialization, and tissue granulation and remodeling. Antimicrobial peptides have been shown to influence all of these cell behaviors in vitro. The cathelicidin PR-39 possesses anti-inflammatory qualities by inhibiting neutrophil oxidase activity, and induces syndecans, heparan sulfate proteoglycans important in wound repair.2,8 Another member of the cathelicidin family, LL-37, has recently been shown to influence the reepithelialization of human skin wounds in organ culture.19
Furthermore, human neutrophil peptide 1, an α-defensin, promotes the expression of type 1 collagen while inhibiting the expression of interstitial collagenase.3 These peptides also possess a broad range of antimicrobial ability, and thus, it has been difficult to discern whether this antimicrobial activity is integral to their positive influence on wound repair. We show that despite loss of antimicrobial activity, the peptide fragment HB-107 of cecropin B retains the ability to aid in wound repair in a murine in vivo model (Table 2, Figures 1 and 2). This benefit observed with HB- 107 was indistinguishable from that seen from the growth factor rhPDGF-BB. While this observation may be partially confounded by the complex formulation of rhPDGF-BB as RegranexTM, the relative efficacy of HB-107 in two distinct vehicles compared to identical vehicle controls confirms the potential benefit of this peptide. These findings further show that this wound repair activity of antimicrobial peptides is not always dependent on direct antimicrobial action.
To begin to investigate the mechanisms of action of HB-107, histological analysis of HB-107–treated wounds was performed. Increased epidermal hyperplasia was seen in HB-107–treated wounds, suggesting that HB-107 may influence keratinocyte proliferation or migration. The recent finding that another cationic antimicrobial peptide, LL-37, plays a role in keratinocyte proliferation19 supports the hypothesis that HB-107 may also carry out its effect by acting directly on keratinocyte growth. Further investigation of this association is warranted.
Because antimicrobial peptides are known to influence angiogenesis9 we next investigated whether increased blood vessel formation might explain the effects seen on wound repair in this study. HB-107–treated wounds, however, did not appear to have any observable effect on angiogenesis. Moreover, the increased granulocytic infiltrate seen in HB-107–treated wounds suggested that HB-107 might work by influencing leukocyte chemotaxis to the wound. This seemed reasonable, as leukocyte phagocytosis and cytokine production are essential factors in wound repair.20,21 To investigate the association between HB-107 and leukocyte chemoattraction, we tested the influence of HB-107 on secretion of IL-8, a potent leukocyte chemokine important in cutaneous wound healing.22,23 We found that HB-107 enhances IL-8 secretion from endothelial cells, suggesting that HB-107 may aid wound repair, in part, by stimulating IL-8–induced chemotaxis. A small effect on IL-8 stimulation was also seen by the scrambled peptide. Additional data testing unrelated, but similarly short amphipathic cationic peptides, showed no stimulation of IL-8 expression in the identical assay conditions (unpublished data, manuscript under review). Thus, the increase in IL-8 seen for the scrambled peptide used as control may reflect the presence of some sequence determinates in this peptide that partially mimic the native HB-107. Current studies to map the functional residues of the HB-107 sequence may help clarify these findings. In vivo studies exploring the association between HB-107 stimulation of IL-8 and wound repair are necessary to further elucidate the role of HB-107 in wound repair.
This study helps refine our understanding of the biological role of antimicrobial peptides in innate defense. Studies have shown that antimicrobial peptides, such as the mammalian cathelicidins and defensins, are essential to innate defense against cutaneous bacterial infection.24–26 However, these peptides also induce angiogenesis, stimulate syndecan expression, and possess chemoattractant properties, elements fundamental to wound repair.2,5,6,9 Our findings indicate that this positive influence on wound repair can be independent of direct antimicrobial activity. Taken together, these data are consistent with the Danger Theory of Immunity, which suggests that the immune system is not as concerned with self vs. nonself as it is with signs of tissue injury from any source.27,28 The wound healing process must integrate defense against infection while simultaneously initiating cellular repair events. Antimicrobial peptides are equipped for host protection by influencing both systems. Thus, as the biological relevance of peptides of innate immunity is further explored, unique complementary functions from these recently appreciated molecules are likely to be elucidated. Further study of the biological role of these peptides and their structure may therefore lead to the development of new therapies for wound repair.
Timothy J. Falla, Lijuan Zhang, Journal of Drugs in Dermatology, (February 8, 2010)
Due to a reduction in estrogen levels peri-and post-menopausal skin exhibit a specific phenotype characterized by reduced thickness, reduced elasticity and increased dryness. Loss of these elements results in increased skin wrinkling and skin sagging. In addition, it is well documented that reduced estrogen levels also negatively impacts dermal wound healing. As a result we tested the hypothesis that molecules capable of stimulating and accelerating wound healing can supplement the skin's diminished activities produced by reduced estrogen. Heptapeptide-7, a fragment of a well-characterized wound healing peptide (HB- 107), was found to stimulate keratinocyte proliferation and migration and induce collagen synthesis. Microarray analysis of Heptapeptide-7-treated dermal keratinocytes revealed an up-regulation of cell division, growth factor and extracellular matrix genes. Validation of this approach was seen in a clinical study of 32 women (mean age 54) in which forehead wrinkles and skin texture were improved with the application of this peptide fragment.
HB-107, a nonbacteriostatic fragment of the antimicrobial peptide cecropin B, accelerates murine wound repair,
Phillip H.A. Lee, MD; Jennifer A. Rudisill, BA; Kenneth H. Lin, BA; Lijuan Zhang, PhD; Scott M. Harris, PhD; Timothy J. Falla, PhD; Richard L. Gallo, MD, PhD, Wound Repair and Regeneration Volume 12, Issue 3, Pages 351-358
Antimicrobial peptides are essential to innate host defense as effectors of pathogen clearance and can modify host cell behaviors to promote wound repair. While these two functions appear interrelated, it is unclear whether the ability to aid in wound repair requires inherent antimicrobial function. We hypothesized that the influence of antimicrobial peptides on wound repair is not dependent on antimicrobial function. To explore this, we analyzed the microbial killing activity of peptide fragments and correlated this with the ability to influence wound repair in mice. HB-107 [Hexapeptide 7] , a peptide lacking antimicrobial activity and originally derived from the antimicrobial cecropin B, showed up to 64 percent improvement in wound repair compared to scrambled peptide and vehicle controls, an effect comparable to treatment with recombinant human platelet-derived growth factor-BB (formulated as RegranexTM). Wounds treated with HB-107 showed keratinocyte hyperplasia and increased leukocyte infiltration. Furthermore, HB-107 stimulated interleukin-8 secretion from cultured endothelial cells, an effect that may explain the increase in leukocyte migration. These findings confirm that antimicrobial peptides can function as effectors of cutaneous wound repair. Moreover, this study furthers our understanding of antimicrobial peptides by showing that their wound repair properties can be independent of antimicrobial function.
Discussion
Antimicrobial peptides have been implicated as positive effectors of wound repair.2,4,18,19 In this study, we tested fragments of antimicrobial peptides for antimicrobial activity and correlated this with their ability to influence wound repair in mice. HB-107, a cationic peptide derived from the moth antimicrobial cecropin B,10 was found to aid in wound repair despite lacking antimicrobial activity. This ability to aid in wound repair was recapitulated in two different vehicles and shown to be comparable to the effect seen by the growth factor rhPDGF-BB, formulated as the commercial product RegranexTM. Further study of HB-107 suggested that it functions by stimulating keratinocyte proliferation and enhancing chemokine- induced leukocyte infiltration.
Normal wound repair involves a precise orchestration of inflammation, epithelialization, and tissue granulation and remodeling. Antimicrobial peptides have been shown to influence all of these cell behaviors in vitro. The cathelicidin PR-39 possesses anti-inflammatory qualities by inhibiting neutrophil oxidase activity, and induces syndecans, heparan sulfate proteoglycans important in wound repair.2,8 Another member of the cathelicidin family, LL-37, has recently been shown to influence the reepithelialization of human skin wounds in organ culture.19
Furthermore, human neutrophil peptide 1, an α-defensin, promotes the expression of type 1 collagen while inhibiting the expression of interstitial collagenase.3 These peptides also possess a broad range of antimicrobial ability, and thus, it has been difficult to discern whether this antimicrobial activity is integral to their positive influence on wound repair. We show that despite loss of antimicrobial activity, the peptide fragment HB-107 of cecropin B retains the ability to aid in wound repair in a murine in vivo model (Table 2, Figures 1 and 2). This benefit observed with HB- 107 was indistinguishable from that seen from the growth factor rhPDGF-BB. While this observation may be partially confounded by the complex formulation of rhPDGF-BB as RegranexTM, the relative efficacy of HB-107 in two distinct vehicles compared to identical vehicle controls confirms the potential benefit of this peptide. These findings further show that this wound repair activity of antimicrobial peptides is not always dependent on direct antimicrobial action.
To begin to investigate the mechanisms of action of HB-107, histological analysis of HB-107–treated wounds was performed. Increased epidermal hyperplasia was seen in HB-107–treated wounds, suggesting that HB-107 may influence keratinocyte proliferation or migration. The recent finding that another cationic antimicrobial peptide, LL-37, plays a role in keratinocyte proliferation19 supports the hypothesis that HB-107 may also carry out its effect by acting directly on keratinocyte growth. Further investigation of this association is warranted.
Because antimicrobial peptides are known to influence angiogenesis9 we next investigated whether increased blood vessel formation might explain the effects seen on wound repair in this study. HB-107–treated wounds, however, did not appear to have any observable effect on angiogenesis. Moreover, the increased granulocytic infiltrate seen in HB-107–treated wounds suggested that HB-107 might work by influencing leukocyte chemotaxis to the wound. This seemed reasonable, as leukocyte phagocytosis and cytokine production are essential factors in wound repair.20,21 To investigate the association between HB-107 and leukocyte chemoattraction, we tested the influence of HB-107 on secretion of IL-8, a potent leukocyte chemokine important in cutaneous wound healing.22,23 We found that HB-107 enhances IL-8 secretion from endothelial cells, suggesting that HB-107 may aid wound repair, in part, by stimulating IL-8–induced chemotaxis. A small effect on IL-8 stimulation was also seen by the scrambled peptide. Additional data testing unrelated, but similarly short amphipathic cationic peptides, showed no stimulation of IL-8 expression in the identical assay conditions (unpublished data, manuscript under review). Thus, the increase in IL-8 seen for the scrambled peptide used as control may reflect the presence of some sequence determinates in this peptide that partially mimic the native HB-107. Current studies to map the functional residues of the HB-107 sequence may help clarify these findings. In vivo studies exploring the association between HB-107 stimulation of IL-8 and wound repair are necessary to further elucidate the role of HB-107 in wound repair.
This study helps refine our understanding of the biological role of antimicrobial peptides in innate defense. Studies have shown that antimicrobial peptides, such as the mammalian cathelicidins and defensins, are essential to innate defense against cutaneous bacterial infection.24–26 However, these peptides also induce angiogenesis, stimulate syndecan expression, and possess chemoattractant properties, elements fundamental to wound repair.2,5,6,9 Our findings indicate that this positive influence on wound repair can be independent of direct antimicrobial activity. Taken together, these data are consistent with the Danger Theory of Immunity, which suggests that the immune system is not as concerned with self vs. nonself as it is with signs of tissue injury from any source.27,28 The wound healing process must integrate defense against infection while simultaneously initiating cellular repair events. Antimicrobial peptides are equipped for host protection by influencing both systems. Thus, as the biological relevance of peptides of innate immunity is further explored, unique complementary functions from these recently appreciated molecules are likely to be elucidated. Further study of the biological role of these peptides and their structure may therefore lead to the development of new therapies for wound repair.
