Efficacy of an agonist of α-MSH, the palmitoyl tetrapeptide-20, in hair pigmentation.

OBJECTIVE: Hair greying (i.e., canities) is a component of chronological ageing and occurs regardless of gender or ethnicity. Canities is directly linked to the loss of melanin and increase in oxidative stress in the hair follicle and shaft. To promote hair pigmentation and reduce the hair greying process, an agonist of α-melanocyte-stimulating hormone (α-MSH), a biomimetic peptide (palmitoyl tetrapeptide-20; PTP20) was developed. The aim of this study was to describe the effects of the designed peptide on hair greying. METHODS: Effect of the PTP20 on the enzymatic activity of catalase and the production of H2 O2 by Human Follicle Dermal Papilla Cells (HFDPC) was evaluated. Influence of PTP20 on the expression of melanocortin receptor-1 (MC1-R) and the production of melanin were investigated. Enzymatic activity of sirtuin 1 (SIRT1) after treatment with PTP20 was also determined. Ex vivo studies using human micro-dissected hairs allowed to visualize the effect of PTP20 on the expression in hair follicle of catalase, TRP-1, TRP-2, Melan-A, ASIP, and MC1-R. These investigations were completed by a clinical study on 15 human male volunteers suffering from premature canities. RESULTS: The in vitro and ex vivo studies revealed the capacity of the examined PTP20 peptide to enhance the expression of catalase and to decrease (30%) the intracellular level of H2 O2 . Moreover, PTP20 was shown to activate in vitro and ex vivo the melanogenesis process. In fact, an increase in the production of melanin was shown to be correlated with elevated expression of MC1-R, TRP-1, and Melan-A, and with the reduction in ASIP expression. A modulation on TRP-2 was also observed. The pivotal role of MC1-R was confirmed on protein expression analysed on volunteer's plucked hairs after 3 months of the daily application of lotion containing 10 ppm of PTP20 peptide. CONCLUSION: The current findings demonstrate the ability of the biomimetic PTP20 peptide to preserve the function of follicular melanocytes. The present results suggest potential cosmetic application of this newly designed agonist of α-MSH to promote hair pigmentation and thus, reduce the hair greying process.

Study of gene expression alteration in male androgenetic alopecia: evidence of predominant molecular signalling pathways.

BACKGROUND: Male androgenetic alopecia (AGA) is the most common form of hair loss in men. It is characterized by a distinct pattern of progressive hair loss starting from the frontal area and the vertex of the scalp. Although several genetic risk loci have been identified, relevant genes for AGA remain to be defined. OBJECTIVES: To identify biomarkers associated with AGA. METHODS: Molecular biomarkers associated with premature AGA were identified through gene expression analysis using cDNA generated from scalp vertex biopsies of hairless or bald men with premature AGA, and healthy volunteers. RESULTS: This monocentric study reveals that genes encoding mast cell granule enzymes, inflammatory mediators and immunoglobulin-associated immune mediators were significantly overexpressed in AGA. In contrast, underexpressed genes appear to be associated with the Wnt/ß-catenin and bone morphogenic protein/transforming growth factor-ß signalling pathways. Although involvement of these pathways in hair follicle regeneration is well described, functional interpretation of the transcriptomic data highlights different events that account for their inhibition. In particular, one of these events depends on the dysregulated expression of proopiomelanocortin, as confirmed by polymerase chain reaction and immunohistochemistry. In addition, lower expression of CYP27B1 in patients with AGA supports the notion that changes in vitamin D metabolism contributes to hair loss. CONCLUSIONS: This study provides compelling evidence for distinct molecular events contributing to alopecia that may pave the way for new therapeutic approaches.

The regulatory role of the tetrapeptide AcSDKP in skin and hair physiology and the prevention of ageing effects in these tissues--a potential cosmetic role.

The naturally occurring tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) recognized as a potent angiogenic factor was shown recently to contribute to the repair of cutaneous injuries. In the current article, we report the ability of AcSDKP to exert a beneficial effect on normal healthy skin and scalp and to compensate for the ageing process. In vitro AcSDKP at 10⁻¹¹-10⁻7 M significantly stimulates the growth of human keratinocytes, fibroblasts and follicle dermal papilla cells. Moreover, it enhances the growth of human epidermal keratinocyte progenitor and stem cells as shown in a clonogenic survival assay. Topical treatment of ex vivo cultured skin explants with 10⁻5 M AcSDKP increases the thickness of the epidermis and upregulates the synthesis of keratins 14 and 19, fibronectin, collagen III and IV as well as the glycoaminoglycans (GAGs). In the ex vivo-cultured hair follicles, AcSDKP promotes hair shaft elongation and induces morphological and molecular modifications matching the criteria of hair growth. Furthermore, AcSDKP at 10⁻¹¹-10⁻7 M was shown to improve epidermal barrier, stimulating expression of three protein components of tight junctions (claudin-1, occludin, ZO-1) playing an important role in connecting neighbouring cells. This tetrapeptide exercises also activation of SIRT1 implicated in the control of cell longevity. Indeed, a two-fold increase in the synthesis of SIRT1 by cultured keratinocytes was observed in the presence of 10⁻¹¹-10⁻7 M AcSDKP. In conclusion, these findings provide convincing evidence of the regulatory role of AcSDKP in skin and hair physiology and suggest a cosmetic use of this natural tetrapeptide to prevent skin ageing and hair loss and to promote the cutaneous regeneration and hair growth.

Human placental low molecular weight factors inhibit the entry into cell cycle of murine pluripotent stem cells.

In 1977, Frindel et al. reported the presence in fetal calf bone marrow of a low molecular factor, the tetrapeptide Ac-N-Ser-Asp-Lys-Pro (AcSDKP), capable of inhibiting in vivo the hematopoietic pluripotent stem cell (CFU-S) recruitment into DNA synthesis and to increase the survival of mice which had received lethal doses of cytosine arabinoside (AraC), a phase-specific drug. Considering the potential clinical importance of CFU-S proliferation inhibitor during anticancer chemotherapy and the importance of monitoring the inhibitor by immunological methods, we tried to determine if a similar inhibitor is present in humans. Preliminary results indicate the presence in human placenta of an inhibitor coeluted with AcSDKP and which is effective in inhibiting murine CFU-S.

AcSDKP, an inhibitor of CFU-S proliferation, is synthesized in mice under steady-state conditions and secreted by bone marrow in long-term culture.

The peptide AcSDKP, isolated from fetal calf bone marrow, is able to prevent DNA synthesis in mouse CFU-S in vivo and in vitro. The molecule is demonstrated here to be constitutively produced in mice and synthesized by bone marrow cells in long term culture.

Enhancement of the adherence of hematopoietic stem cells to mouse bone marrow-derived stromal cell line MS-1-T by a tetrapeptide acetyl-N-Ser-Asp-Lys-Pro.

The tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) has been shown to inhibit in vivo the hematopoietic stem cell (spleen colony-forming unit; CFU-S) entry into cell cycle in cytosine arabinoside-treated mice. Our data showed that AcSDKP has no effect on interleukin 3 (IL-3)-dependent DA-1 cell proliferation or on granulocyte-macrophage colony-forming cell and mast cell colony formation, whereas it enhances the adherence of CFU-S to the bone marrow-derived hematopoietic supportive stromal cell line MS-1-T. AcSDKP suppresses MS-1-T proliferation but does not modify granulocyte-macrophage colony-stimulating activity secretion by these cells. This suggests that the peptide does not counteract the activity of the IL-3 receptor on CFU-S but acts on MS-1-T and in particular at the level of CFU-S/MS-1-T interactions.

Lisinopril, an angiotensin I-converting enzyme inhibitor, prevents entry of murine hematopoietic stem cells into the cell cycle after irradiation in vivo.

The hemoregulatory peptide N-Acetyl-Ser-Asp-Lys-Pro (AcSDKP) has been shown in vivo to inhibit the cycling of murine hematopoietic stem cells triggered into S-phase by either cytotoxic drug administration or irradiation. This property, further confirmed using in vitro models, demonstrates that the peptide has an in vivo protective effect on the hematopoietic system. AcSDKP has been shown to be a physiological substrate of angiotensin I-converting enzyme (ACE), which catabolizes the peptide through a dipeptidasic activity. Thus, oral administration of ACE inhibitor to humans has led to an increase in the plasma AcSDKP concentration. In the present paper, we report on the in vivo effect of lisinopril, an ACE inhibitor, on the proliferative status of murine hematopoietic stem cells triggered into S-phase by irradiation. Administration of lisinopril (10 mg/kg) 1 hour after irradiation led to a 90 to 100% inhibition of murine plasma ACE activity as observed during the first 4 hours postirradiation. This inhibition was correlated with a 600% increase in the endogenous plasma AcSDKP level and a total suppression at 24 hours of entry of the hematopoietic stem cell into the cell cycle. We discuss the possible role of ACE in the regulation of hematopoietic stem cell proliferation through control of the AcSDKP concentration.

Renal and metabolic clearance of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) during angiotensin-converting enzyme inhibition in humans.

We investigated the contributions of angiotensin-converting enzyme (ACE) and glomerular filtration to creating the new metabolic balance of the hemoregulatory peptide N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) that occurs during acute and chronic ACE inhibition in healthy subjects. We also studied the effect of chronic renal failure on the plasma concentration of AcSDKP during long-term ACE inhibitor (ACEI) treatment or in its absence. In healthy subjects, a single oral dose of 50 mg captopril (n=32) and a 7-day administration of 50 mg captopril BID (n=10) resulted in a respective 42-fold (range, 18- to 265-fold) and 34-fold (range, 24-fold to 45-fold) increase in the ratio of urinary AcSDKP to creatinine accompanied by a 4-fold (range, 2- to 6.8-fold) and 4.8-fold (range, 2.6- to 11.8-fold) increase in plasma AcSDKP levels. Changes in plasma AcSDKP and in vitro ACE activity over time showed an intermittent reactivation of ACE between each captopril dose. In subjects with chronic renal failure (creatinine clearance<60 mL/min per 1.73 m2), plasma AcSDKP levels were 22 times higher (95% confidence interval, 15 to 33) in the ACEI group (n=35) than the control group (n=23); in subjects with normal renal function, they were only 4.1 times higher (95% confidence interval, 3.2 to 5.3) in the ACEI group (n=19) than the non-ACEI group (n=21). Renal failure itself led to a slight increase in plasma AcSDKP concentration. In conclusion, intermittent reactivation of ACE between doses of an ACEI is the major mechanism accounting for the lack of major AcSDKP accumulation during chronic ACE inhibition in subjects with normal renal function.

The mechanism of action of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) in the control of haematopoietic stem cell proliferation.

The mechanism of action of the haemoregulatory tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP, M(r) = 487 amu), was investigated using an in vitro assay of a murine high proliferative potential colony-forming cell (HPP-CFC) which responds to proliferation regulators of the haematopoietic stem cell population. AcSDKP had no direct inhibitory effect on the number, or the proportion in S phase, of the committed granulocyte-macrophage progenitor (GM-CFC), or cycling HPP-CFC populations. However, AcSDKP blocked the action of a stimulator of haematopoietic stem cell proliferation, preventing the switching of quiescent HPP-CFC into cell cycle. It would appear that AcSDKP exerts its inhibitory haemoregulatory role indirectly, by preventing stimulator action on haematopoietic stem cells.

The antiproliferative activity of the tetrapeptide Acetyl-N-SerAspLysPro, an inhibitor of haematopoietic stem cell proliferation, is not mediated by a thymosin beta 4-like effect on actin assembly.

Acetyl-N-SerAspLysPro (AcSDKP), known as a negative regulator of haematopoiesis, has been principally reported as an inhibitor of haematopoietic pluripotent stem cell proliferation. The tetrapeptide sequence is identical to the N-terminus of thymosin beta 4 (T beta 4), from which it has been suggested that it may be derived. Recently, evidence was shown that T beta 4 plays a role as a negative regulator of actin polymerization leading to the sequestration of its monomeric form. The structural similarity between the N-terminus of T beta 4 and AcSDKP has raised the possibility that AcSDKP may also participate in intracellular events leading to actin sequestration. The effect of T beta 4 on the proliferation of haematopoietic cells was compared to that of AcSDKP. The results revealed that T beta 4, like AcSDKP, exerts an inhibitory effect on the entry of murine primitive bone marrow cells into cell cycle in vitro. Qualitative electrophoretic analysis and quantitative polymerization assays were used to investigate the role of AcSDKP in actin polymerization. AcSDKP does not affect actin assembly at concentrations up to 50 microM, and does not compete with T beta 4 for binding to G-actin. These results suggest that AcSDKP is not involved in cell cycle regulation via an effect on the process of actin polymerization.

Modulation of protein expression in murine bone marrow cells following in-vivo cytosine arabinoside treatment.

The technique of SDS-PAGE followed by autoradiography was applied to study the changes in protein synthesis occurring in murine bone marrow cells in response to AraC administration. It was found that following AraC injection the medullary population undergoes pronounced changes in protein synthesis. Marked increases were noted in the 20, 28 and 70 kD protein labelling, concomitantly with CFU-S stimulating activity of the AraC treated mice bone marrow conditioned medium.

Suppression of mast cell colony formation by a low molecular weight fraction of fetal calf bone marrow extract.

A semi-purified fraction extracted from fetal calf bone marrow was previously shown to contain a tetrapeptide N-Ac-Ser-Asp-Lys-Pro which inhibits in mice, hematopoietic stem cell entry into the cell cycle. This peptide however, did not exhibit any effect on either IL-3 nor GM-CSF dependent cell growth. We report herein that a semi-purified fraction also contains another activity which is antagonistic to IL-3. Addition of the fraction in vitro decreased IL-3 dependent mast cell colony formation. Growth of IL-3 dependent cell lines (DA-1 and FDC-P2) was also suppressed. No effect was observed in the same dose range on granulocyte-macrophage colony formation nor on IL-3 independent cell growth.

Formation of acetyl-Ser-Asp-Lys-Pro, a new regulator of the hematopoietic system, through enzymatic processing of thymosin beta 4.

The demonstration that AcSDKP, a new regulator of the hematopoietic system, is formed in the bone marrow by a one-step enzymatic maturation processing of thymosin beta 4 (T beta 4) is presented. AcSDKP and T beta 4 were both detected in bone marrow cells (BMC). Incubation of [3H]T beta 4 with either intact or lysed BMC led to the formation of [3H]AcSDKP, whereas the labeled tetrapeptide was not degraded under these conditions. Model enzymatic degradation of T beta 4 carried out with bacterial enzymes suggests that a mammalian endoproteinase Asp-N might be involved in the formation of AcSDKP through the specific cleavage of the Pro4-Asp5 peptidic bond of T beta 4. In contrast, alpha-prolyl-endopeptidase was ineffective in carrying out a similar processing.

Modulating role of glucose on magnesium transport in rat erythrocytes.

Magnesium efflux from rat erythrocytes has been shown to be inhibited by a plasma fraction containing glucose. Therefore, we investigated the effect of D-glucose on erythrocyte magnesium transport. We show the inhibitory activity of this hexose on sodium (Na(+))-independent erythrocyte magnesium (Mg(2+)E) efflux. Inhibitory effects of D-mannose, 2-deoxy-D-glucose, and D-fructose on Mg(2+)E efflux also were demonstrated. Moreover, the suppression of the inhibitory activity of glucose on Mg(2+)E efflux was shown to be associated with the inhibition of glucose transport by cytochalasin B and phloretin. Together these data suggest a possible implication of the glucose carrier GLUT-1 in the regulation of Mg(2+) transport.

Further purification of a CFU-S inhibitor: in vivo effects after cytosine arabinoside treatment.

This paper describes a large scale extraction procedure which allows the preparation of a stable CFU-S inhibitor from fetal calf bone marrow. The use of BioGel P-2 gels results in an increase of the specific activity of the inhibitor as well as in the yield of the preparation. When injected into mice, the inhibitory fraction (Ve/Vo 1.17-1.8) prevent CFU-S entry into cycle after cytosine arabinoside at a dose of 4 micrograms per mouse. When administered during lethal protocols of Ara-C treatment, it significantly increases the percentage of surviving animals. Thus, this low molecular weight factor (below 2,000 D), devoid of species-specificity, enhances the tolerance of animals to high doses of chemotherapy and might be of interest in cancer treatment.

Catabolism of the tetrapeptide N-Ac-Ser-Asp-Lys-Pro (AcSDKP), an inhibitor of hematopoietic stem cell (CFU-S) proliferation, following in vitro incubation with hematopoietic tissues from normal and leukemic mice.

The comparative degradation of N-Ac-Ser-Asp-Lys-Pro (AcSDKP), a negative regulator controlling the proliferation of the hematopoietic pluripotent stem cell, was investigated following incubation with plasma, bone marrow and spleen cells from normal mice and mice bearing a transplantable myeloid leukemia. Using the tetrapeptide, specifically radiolabelled in the lysyl residue, degradation of [3H]AcSDKP was followed by measurement of [3H]Lys formation resulting from its catabolism. It was shown that already after 1 h the degradation of AcSDKP in plasma from leukemic mice was higher compared to that following incubation in plasma from normal mice, whereas incubation with bone marrow cells exhibits a small difference only after 4 hours incubation. However, no increase of AcSDKP catabolic activity was observed following incubation with spleen cells from leukemic animals when compared with incubation of normal spleen cells.

Both plants Sebastiania chamaelea from Niger and Chrozophora senegalensis from Senegal used in African traditional medicine in malaria treatment share a same active principle.

ETHNOPHARMACOLOGICAL RELEVANCE: Based on ethnobotanical data obtained from Nigerien and Senegalese traditional healers, two Euphorbiaceae plants, Sebastiania chamaelea and Chrozophora senegalensis, traditionally used to treat malaria, were selected for further investigations. MATERIALS AND METHODS: Plant extracts were prepared with different solvents and tested both in vitro on several strains of Plasmodium falciparum, and in vivo to evaluate their antiplasmodial properties and isolate their active principles. RESULTS: With IC50 values around 6.5µg/ml and no significant cytotoxicity (>50µg/ml), the whole plant aqueous extract from S. chamaelea showed the best in vitro results. In vitro potentiation assays showed strong synergistic activity of S. chamaelea extract with the antiplasmodial drug chloroquine on the chloroquine-resistant P. falciparum strain W2-Indochina. In other respects, the aqueous crude extract of C. senegalensis leaves showed the most significant antiplasmodial activity in vitro (IC50 values less than 2µg/ml). We also demonstrated the prophylactic activity of C. senegalensis in vivo in a murine malaria model. Bioassay-guided fractionation of aqueous extracts of these plants enabled the isolation and identification of ellagic acid (EA, 1) as the main compound responsible for their antiplasmodial activity. Together with EA, other derivatives belonging to different chemical groups were isolated but showed moderate antimalarial activity: gallic acid (2), brevifolin carboxylic acid (3), protocatechuic acid (4), corillagin (5), rutin (6) and 3,4,8,9,10-pentahydroxy-dibenzo(b,d)pyran-6-one (7). The structures were determined by the usual spectroscopic methods and by comparison with published data. Furthermore, we report here the quantification of compound 1 (EA) by RP-HPLC in the dried extracts of these plants, reported for the first time in both these species, and possessing the highest in vitro antiplasmodial activity with IC50 values from 180 to 330nm. CONCLUSIONS: These in vitro and in vivo results support the traditional use in Africa of crude extracts of both S. chamaelea and C. senegalensis as an antimalarial treatment and prove the significant antiplasmodial property of EA.

The molecular specificity of action of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) in the control of hematopoietic stem cell proliferation.

The hemoregulatory tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP, M(r) = 487 amu) prevents the recruitment of hematopoietic stem cells into S phase. AcSDKP does not possess inherent inhibitory activity against hematopoietic stem cells, rather it appears to act by "blocking" the action of a hematopoietic stem cell proliferation stimulator present in extracts of regenerating hematopoietic tissue. The molecular specificity of this action was investigated using a number of peptide analogues of AcSDKP and evaluating their ability to "block" the recruitment of a primitive murine hematopoietic precursor (high proliferative potential colony forming cell HPP-CFC) into S phase following incubation with a hematopoietic stem cell proliferation stimulator. The capacity of AcSDKP to compromise the action of the hematopoietic stem cell proliferation stimulator was not evident for either AcSDDKP or AcSD beta KP, two structurally distinct forms of the molecule; similar no stimulator-"blocking" activity was observed for the tripeptide Ala-Asp-Lys (ADK, M(r) = 332 amu), while the tripeptide Ser-Asp-Lys (SDK, M(r) = 348 amu) was active. It would appear that the hemoregulatory action of AcSDKP is specific and that the tripeptide sequence SDK may be a significant component of the molecule.

Optimization of cell culture conditions for the evaluation of the biological activities of the tetrapeptide N-Acetyl-Ser-Asp-Lys-Pro, a natural hemoregulatory factor.

The present study attempts to define the difficulties in evaluating the properties of the hemoregulatory peptide AcSDKP using in vitro assays. In fact, in the presence of sera, which are generally added to basic culture media, AcSDKP is catabolized by proteases present in the serum. The kinetics of AcSDKP degradation depends on the nature and on the concentration of the added serum. In in vitro conditions, the half life of this peptide can be increased by the addition of 1 microM captopril, a metalloprotease inhibitor. Thus, these points need to be considered in designing experiments to study the effects of AcSDKP.