Role of kinin receptors in skin pigmentation.

Previous studies have shown that all kinin system is constitutively expressed in the normal and inflamed skin, with a potential role in both physiological and pathological processes. However, the understanding regarding the involvement of the kinin system in skin pigmentation and pigmentation disorders remains incomplete. In this context, the present study was designed to determine the role of kinins in the Monobenzone (MBZ)-induced vitiligo-like model. Our findings showed that MBZ induces higher local skin depigmentation in kinin receptors knockout mice (KOB1R, KOB2R and KOB1B2R) than in wild type (WT). Remarkably, lower levels of melanin content and reduced ROS generation were detected in KOB1R and KOB2R mice treated with MBZ. In addition, both KOB1R and KOB2R show increased dermal cell infiltrate in vitiligo-like skin, when compared to WT-MBZ. Additionally, lack of B1R was associated with greater skin accumulation of IL-4, IL-6, and IL-17 by MBZ, while KOB1B2R presented lower levels of TNF and IL-1. Of note, the absence of both kinin B1 and B2 receptors demonstrates a protective effect by preventing the increase in polymorphonuclear and mononuclear cell infiltrations, as well as inflammatory cytokine levels induced by MBZ. In addition, in vitro assays confirm that B1R and B2R agonists increase intracellular melanin synthesis, while bradykinin significantly enhanced extracellular melanin levels and proliferation of B16F10 cells. Our findings highlight that the lack of kinin receptors caused more severe depigmentation in the skin, as well as genetic deletion of both B1/B2 receptors seems to be linked with changes in levels of constitutive melanin levels, suggesting the involvement of kinin system in crucial skin pigmentation pathways.

Anti-proliferative and anti-inflammatory effects of the application of baclofen cream, a GABAB receptor agonist, on skin inflammation in mice.

Previous studies have demonstrated the role of γ-aminobutyric acid type B (GABAB) receptors in skin-related conditions and pain. However, most studies have focused on the main effects of GABAB on the central nervous system. Therefore, this study has aimed to determine the potential topical anti-inflammatory and anti-proliferative effects of baclofen cream in an inflammatory skin disease model. The effects of the baclofen cream were evaluated using acute and chronic models of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation in mouse ears. Histological and immunohistochemical evaluations were performed using an ear oedema assay. The effect of baclofen on keratinocyte proliferation was assessed in PAM212, the murine keratinocyte cell line. The results demonstrate that a single topical application of 5% baclofen, 7.5% baclofen, and 1% dexamethasone each inhibited acute TPA-induced ear oedema (58.94 ± 6.14%, 47.73 ± 11.26%, and 87.33 ± 4.59%, respectively). These results were confirmed by histological analysis. In the chronic model, baclofen (5%) and dexamethasone (1%) each inhibited ear oedema and the maximum inhibitory effect was reached at the end of the experiment (9th day of TPA application) with a percentage inhibition of 54.60 ± 6.15% for baclofen and 71.68 ± 3.45% for dexamethasone, when compared to the vehicle. These results were confirmed by histological analysis. Baclofen and dexamethasone also reduced proliferating cell nuclear antigen expression by 62.01 ± 6.65% and 70.42 ± 6.11%, respectively. However, baclofen did not inhibit keratinocyte proliferation in PAM212 cells. In conclusion, these results demonstrate that baclofen exhibits notable topical antiproliferative and anti-inflammatory properties and could be a potential therapeutic alternative for treating inflammatory and proliferative skin diseases.

miRNA-203b-3p Induces Acute and Chronic Pruritus through 5-HTR2B and TRPV4.

Growing evidence indicates that transient receptor potential (TRP) channels contribute to different forms of pruritus. However, the endogenous mediators that cause itch through transient receptor potential channels signaling are poorly understood. In this study, we show that genetic deletion or pharmacological antagonism of TRPV4 attenuated itch in a mouse model of psoriasis induced by topical application of imiquimod. Human psoriatic lesions showed increased expression of several microRNAs, including the miR-203b-3p, which induced a calcium ion response in rodent dorsal root ganglion neurons and scratching behavior in mice through 5-HTR2B activation and the protein kinase C‒dependent phosphorylation of TRPV4. Computer simulation revealed that the miR-203b-3p core sequence (GUUAAGAA) that causes 5-HTR2B/TRPV4-dependent itch targets the extracellular side of 5-HTR2B by interacting with a portion of the receptor pocket consistent with its activation. Overall, we reveal the unconventional pathophysiological role of an extracellular microRNA that can behave as an itch promoter through 5-HTR2B and TRPV4.

Role of nitric oxide, bradykinin B2 receptor, and TRPV1 in the airway alterations caused by simvastatin in rats.

Dry cough has been reported in patients receiving statin therapy. However, the underlying mechanism or other possible alterations in the airways induced by statins remain unknown. Thus, the aim of this study was to evaluate whether simvastatin promotes alterations in airways, such as bronchoconstriction and plasma extravasation, as well as the mechanism involved in these events. Using methods to detect alterations in airway resistance and plasma extravasation, we demonstrated that simvastatin [20 mg/kg, intravenous (i.v.)] caused plasma extravasation in the trachea (79.8 + 14.8 µg/g/tissue) and bronchi (73.3 + 8.8 µg/g/tissue) of rats, compared to the vehicle (34.2 + 3.6 µg/g/tissue and 29.3 + 5.3 µg/g/tissue, respectively). NG-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg, intraperitoneal), a nitric oxide (NO) synthase inhibitor, Icatibant [HOE 140, 10 nmol/50 µl, intratracheal (i.t.)], a bradykinin B2 antagonist, and capsazepine (100 nmol/50 µl, i.t.), a TRPV1 antagonist, attenuated simvastatin-induced plasma extravasation. Simvastatin (5, 10 and 20 mg/kg) did not cause bronchoconstriction per se, but exacerbated the bronchoconstrictive response to bradykinin (30 nmol/kg, i.v.), a B2 agonist (0.7 + 0.1 ml/H2O), or capsaicin (30 nmol/kg, i.v.), a TRPV1 agonist (0.8 + 0.1 ml/H2O), compared to the vehicle (0.1 + 0.04 ml/H2O and 0.04 + 0.01 ml/H2O, respectively). The bronchoconstriction elicited by bradykinin (100 nmol/kg, i.v.) in simvastatin non-treated rats was inhibited by L-NAME. The exacerbation of bronchoconstriction induced by bradykinin or capsaicin in simvastatin-treated rats was inhibited by L-NAME, HOE 140 or capsazepine. These results suggest that treatment with simvastatin promotes the release of bradykinin, which, via B2 receptors, releases NO that can then activate the TRPV1 to promote plasma extravasation and bronchoconstriction.

B1 and B2 kinin receptor blockade improves psoriasis-like disease.

BACKGROUND AND PURPOSE: The entire kallikrein-kinin system is present in the skin, and it is thought to exert a relevant role in cutaneous diseases, including psoriasis. The present study was designed to evaluate the relevance of kinin receptors in the development and progression of a model of psoriasis in mice. EXPERIMENTAL APPROACH: The effects of kinin B1 and B2 receptor knockout and of kinin receptor antagonists (SSR240612C or FR173657) were assessed in a model of psoriasis induced by imiquimod in C57BL/6 mice. Severity of psoriasis was assessed by histological and immunohistochemical assays of skin, along with objective scores based on the clinical psoriasis area and severity index. KEY RESULTS: Both kinin receptors were up-regulated following 6 days of imiquimod treatment. Kinin B1 and B2 receptor deficiency and the use of selective antagonists show morphological and histological improvement of the psoriasis hallmarks. This protective effect was associated with a decrease in undifferentiated and proliferating keratinocytes, decreased cellularity (neutrophils, macrophages, and CD4+ T lymphocytes), reduced γδ T cells, and lower accumulation of IL-17. The lack of B2 receptors resulted in reduced CD8+ T cells in the psoriatic skin. Relevantly, blocking kinin receptors reflected the improvement of psoriasis disease in the well-being behaviour of the mice. CONCLUSIONS AND IMPLICATIONS: Kinins exerted critical roles in imiquimod-induced psoriasis. Both B1 and B2 kinin receptors exacerbated the disease, influencing keratinocyte proliferation and immunopathology. Antagonists of one or even both kinin receptors might constitute a new strategy for the clinical treatment of psoriasis.

Baccharis dracunculifolia (Asteraceae) essential oil displays anti-inflammatory activity in models of skin inflammation.

ETHNOPHARMACOLOGICAL RELEVANCE: Baccharis dracunculifolia (Asteraceae) is a commonly used plant in traditional medicine known as "alecrim-do-campo". Popularly it has been used as an immunostimulant, antibiotic, anti-inflammatory among other applications. So far, only a few studies have investigated the B. dracunculifolia anti-inflammatory effect and none has investigated the effectiveness of essential oil on skin diseases. AIM OF THE STUDY: The study aimed at evaluating the topical anti-inflammatory activity of B. dracunculifolia essential oil (BdEO) in mice models of acute and chronic skin inflammation. MATERIALS AND METHODS: BdEO was obtained from leaves and it was analyzed with Gas Chromatograph. Topical anti-inflammatory activity of BdEO (0.1, 0.3 and 1.0 mg/ear) was evaluated in Arachidonic Acid or TPA-induced acute and chronic skin inflammation in mice. Parameters such edema, cell migration and keratinocytes proliferation were evaluated. In addition, safety and a possible mechanism of action for BdEO essential oil were also investigated. RESULTS: Our results indicate that mainly terpenoids compounds compose BdEO. In addition, topical treatment with BdEO inhibited inflammatory parameters in both acute and chronic models of skin inflammation. This protective effect was associated with reduced edema formation, smaller cellular influx into the inflamed tissue and reduction of keratinocytes hyperproliferation. Although BdEO appears to exert its anti-inflammatory effect through a corticosteroid pathway, no local or systemic side effects were observed. CONCLUSION: Taken together, the present results showed that the essential oil obtained by hydrodistillation from B. dracunculifolia leaf samples exhibit remarkable topical anti-inflammatory properties. Therefore, our study demonstrated evidence for BdEO topical anti-inflammatory efficacy and safety, suggesting that it could be considered for developing of a new phytotherapeutic formulation as treatment for skin diseases.

Expanding the anti-inflammatory potential of Moringa oleifera: topical effect of seed oil on skin inflammation and hyperproliferation.

ETHNOPHARMACOLOGICAL RELEVANCE: Popularly used in India and sub-Hymalaian region, Moringa oleifera (Moringaceae) is associated with healing properties demonstrated in its use as treatment of acute and chronic skin diseases. Our study aimed at investigating the effects of M. oleifera seed oil (MOSO) in animal models for inflammatory and hyperproliferative skin conditions. MATERIALS AND METHODS: MOSO was analyzed using gas chromatography/mass spectrometry. The anti-inflammatory and anti-hyperproliferative effects of treatment with either MOSO or oleic acid (OA), its main constituent, was evaluated. Acute and chronic inflammation was induced by applying 12-O-Tetradecanoylphorbol-13-acetate (TPA) and acute inflammation with either Arachidonic Acid (AA) or Phenol onto the ear of Swiss mice. Systemic activity and the influence of glucocorticoid receptors (GC) was also evaluated. RESULTS: Topical application of MOSO and OA inhibited ear edema caused by TPA, and Phenol. Only MOSO inhibited ear edema induced by AA. Neutrophil migration was also inhibited by treatment with MOSO. Topical application of MOSO, but not OA, significantly reduced chronic skin inflammation and epidermal hypertrophy induced by multiple TPA applications. Pre-treatment with GC antagonist mifepristone reversed the anti-inflammatory effect of MOSO and OA on the TPA model. Repeated administration of MOSO show a similar effect to dexamethasone on thymus weight, though MOSO did not present any influence on skin thickness, as well as in the weight of the spleen, adrenal gland and lymph node. CONCLUSION: The results suggest that MOSO is effective as a treatment for skin diseases that rely on keratinocyte hyperproliferation. OA is also effective in acute inflammation. Both MOSO and OA depend on GC activation for anti-inflammatory effect but do not exhibit the same adverse effects seen in topical treatment with dexamethasone. We hereby evidence the use of MOSO as a topical anti-inflammatory agent in inflammatory skin diseases, thus, expanding its therapeutic potential.

Preclinical study of the topical anti-inflammatory activity of Cyperus rotundus L. extract (Cyperaceae) in models of skin inflammation.

ETHNOPHARMACOLOGICAL RELEVANCE: Cyperus rotundus L. (Cyperaceae) is considered one of the most widely distributed plant species in the world, especially in tropical and subtropical regions. In addition, it is commonly used in India, China and Japan in traditional medicine to treat different diseases, including dermatitis and other skin disorders. AIM OF THE STUDY: To investigate the topical anti-inflammatory activity of C. rotundus rhizome ethanolic extract in models of acute and chronic dermatitis. MATERIALS AND METHODS: Phytochemical analysis was carried out using High-performance liquid chromatography-ultraviolet detection (HPLC/UV) to determine the presence of quercetin and chlorogenic acid in C. rotundus extract. Topical anti-inflammmatory effects of C. rotundus extract were evaluated on arachidonic acid (AA) and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation in mice. Skin biopsies were collected and submitted to histological and enzymatic analysis to evaluate the C. rotundus effect in leukocyte migration into inflamed tissue. Antiproliferative activity of C. rotundus was confirmed by PCNA immunostained cell analysis. Systemic and possible adverse effects of topical treatment with C. rotundus were evaluated by the skin atrophy and same organ weights. In addition, the glucocorticoid receptor (GR) antagonist mifepristone was used to investigate possible GR-mediated mechanisms of action. RESULTS: The phytochemical analysis show that C. rotundus ethanol extract contains 45 µg/g of chlorogenic acid. Topical treatment with C. rotundus extract reduced ear edema and cellular infiltrate in acute and chronic skin inflammation models. Moreover, mice topically treated with C. rotundus exhibited decrease in TPA-induced keratinocyte hyperproliferation. Relevantly, topical treatment with C. rotundus did not caused skin atrophy or changes in lymphoid organ weight. The anti-inflammatory effect of C. rotundus was not influenced by the GR antagonist. CONCLUSION: The results here demonstrate for the first time the topical anti-inflammatory and antiproliferative efficacy of C. rotundus extract, suggesting that the extract could be a potential new therapeutic tool for the treatment of inflammatory skin disorders.

Corticoid-like anti-inflammatory effect of Vochysia bifalcata Warm.: Preclinical evidence of efficacy and safety.

ETHNOPHARMACOLOGICAL RELEVANCE: Vochysia bifalcata is a Brazilian native tree commonly used for economic purpose in the reforestation and in the manufacture of products. However, the potential usage of other parts of the plant is usually wasted. Besides, other species of Vochysia are well known for its anti-inflammatory action. AIM OF THE STUDY: In this study we evaluate the possible anti-inflammatory activity of the hydroethanolic extract from the leaves of V. bifalcata in models of mice skin inflammation. MATERIALS AND METHODS: Effects of V. bifalcata were evaluated in croton oil-induced acute and chronic skin inflammation. The role of glucocorticoid receptors in the extract effect was assessed by using a glucocorticoid receptor antagonist and by a specific binding assay. Possible adverse effects were evaluated after multiple treatments with the extract in a skin atrophy model. RESULTS: Topical application of V. bifalcata reduced ear edema formation, cell infiltration and interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels. In the chronic model, besides edema formation and cell infiltration, the extract inhibited epidermal hyperproliferation and Proliferating Cell Nuclear Antigen expression. V. bifalcata seems to act by biding to corticoid receptors, however it did not induce corticoid related undesirable effects. CONCLUSION: Hydroethanolic extract from leaves of V. bifalcata could be an interesting tool in the search for new anti-inflammatory and antiproliferative agents for the treatment of skin disorders.

Tabernaemontana catharinensis leaves effectively reduce the irritant contact dermatitis by glucocorticoid receptor-dependent pathway in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Tabernaemontana catharinensis, popularly known as snakeskin, is used in traditional medicine to treat skin inflammatory disorders. To confirm the topical anti-inflammatory effect of T. catharinensis leaves, we evaluated the therapeutic effect of crude extract (TcE) and its different fractions on irritant contact dermatitis model in mice and verified its anti-inflammatory action mechanism. MATERIALS AND METHODS: The qualitative phytochemical analysis of TcE and its dichloromethane, n-butanol and ethyl acetate fractions was performed by UHPLC-ESI-HRMS. The gel accelerated stability was performed to ensure the effectiveness formulation. We investigated the TcE' inhibitory effect, its fractions and a gel formulation containing TcE in irritant contact dermatitis models induced by unique (1000 µg/ear) and multiple (400 µg/ear) croton oil application, evaluated by the ear edema formation, inflammatory cell infiltration (MPO activity measurement and histological procedure) and pro-inflammatory cytokines levels. The action glucocorticoid-like of TcE was investigated using a glucocorticoid receptor antagonist (mifepristone; 50 mg/kg, s.c.). RESULTS: The treatments (10 µg/ear) reduced the ear edema and MPO activity by 100% and 94 ± 3% (TcE) 85 ± 4% and 88 ± 3% (dichloromethane fraction), 83 ± 6% and 73 ± 11% (n-butanol fraction) and 86 ± 6% and 93 ± 4% (ethyl acetate fraction) and 100% (dexamethasone solution), respectively to the acute ICD model. The TcE and dexamethasone gel (15 mg/ear) also reduced by 66 ± 6% and 70 ± 5% the ear edema and by 58 ± 14% and 84 ± 4% the MPO activity, respectively. To the chronic ICD model, the TcE and dexamethasone (10 µg/ear) also reduced the ear edema (66 ± 6% and 70 ± 5%) and the MPO activity (58 ± 14% and 84 ± 4%); on the 9th day of the experiment. TcE and dexamethasone also reduced the pro-inflammatory cytokines (MIP-2, IL-1ß and TNF-α) levels in acute ICD model induced by croton oil. Besides, mifepristone prevented the topical anti-edematogenic effect of TcE' and dexamethasone' solutions by 97 ± 9% to TcE and 75 ± 15% to dexamethasone. The accelerated stability study of T.catharinensis gels showed no relevant changes at low temperatures. The dereplication of the TcE and fractions revealed the presence of indole alkaloids, triterpenes, and flavonoids by UHPLC-ESI-HRMS. These classes of compounds are known in the literature for present potential anti-inflammatory action, supporting the results obtained. CONCLUSION: The results confirm the topical popular use ofT.catharinensis leaves in the treatment of skin inflammation and demonstrate the TcE' potential for the development of a promising topical anti-inflammatory agent to treat inflammatory disorders.

Tabernaemontana catharinensis leaves exhibit topical anti-inflammatory activity without causing toxicity.

BACKGROUND: Tabernaemontana catharinensis, popularly known as snake skin, has been empirically used as an anti-inflammatory to treat cutaneous skin disorders. However, no study proves its effectiveness as a topical anti-inflammatory. STUDY DESIGN: We investigated the topical anti-inflammatory effect of T.catharinensis leaves crude extract (TcE) in irritant contact dermatitis models in mice and its preliminary toxicity profile. METHODS: The topical anti-inflammatory effect was evaluated by ear thickness measurement, inflammatory cell infiltration (MPO activity measurement and histological procedure) and cytokines levels. TcE qualitative phytochemical analysis was performed by UHPLC-ESI-HRMS and the TcE effect (therapeutic dose; 10 µg/ear) on preliminary toxicological parameters was also evaluated (on the 14°â€¯day of experiment). RESULTS: TcE (10 µg/ear) prevented the development of ear edema induced by cinnamaldehyde, capsaicin, arachidonic acid, phenol, and croton oil with maximum inhibition of 100% to cinnamaldehyde, arachidonic acid, phenol, and croton oil and 75 ±â€¯6% to capsaicin. Besides, the TcE (10 µg/ear) also prevented the increase of MPO activity by 96 ±â€¯2%, 48 ±â€¯7%, 100%, 87 ±â€¯8%, and 93 ±â€¯4%, respectively, to the same irritant agents. The positive controls also prevented both ear edema and the increased of MPO activity by 100% and 42 ±â€¯8% (HC-030031), 54 ±â€¯6% and 80 ±â€¯4% (SB-366791), 100% and 54 ±â€¯5% (indomethacin), 100% and 80 ±â€¯4% (dexamethasone in skin inflammation model induced by phenol) and 100% and 97 ±â€¯3% (dexamethasone in inflammation model induced by croton oil), respectively. TcE also prevented the inflammatory cells infiltration and the increase of MIP-2, IL-1ß and TNF-α levels irritant agents-induced. TcE topical anti-inflammatory effect may be attributed to the combined effect of indole alkaloids, terpenes, and phenolic compounds found in the extract and identified by dereplication method. The TcE' therapeutic dose proved to be safe in preliminary toxicological tests. CONCLUSION: Our results suggest that TcE could be an interesting strategy for the treatment of inflammatory diseases.

Aliskiren: Preclinical evidence for the treatment of hyperproliferative skin disorders.

Psoriasis is a complex inflammatory and hyperproliferative skin disease. The pathogenesis and mechanisms involved are not completely understood, which makes treatment a difficult issue. Angiotensin II, the most active peptide of the renin-angiotensin system, seems to be involved in processes related to psoriasis pathogenesis, such as inflammation and cell proliferation. The aim of this study was to investigate the influence of renin inhibition on inflammation parameters and keratinocyte proliferation in a mouse model of chronic skin inflammation induced by croton oil. Aliskiren had anti-inflammatory effects by reducing levels of tumor necrosis factor-α and interleukin -6, and by inhibiting myeloperoxidase activity. Aliskiren also showed antiproliferative activity by reducing epidermal hyperplasia and proliferating cell nuclear antigen levels. Aliskiren treatment did not induce alterations in the cardiovascular system, normal skin thickness, and organ weight. These results suggest that aliskiren could be a valuable tool to be incorporated in the treatment of hyperproliferative and inflammatory skin disorders such as psoriasis.

Involvement of the TRPV1 receptor in plasma extravasation in airways of rats treated with an angiotensin-converting enzyme inhibitor.

Angiotensin-converting enzyme inhibitors (ACEIs) are widely used in the treatment of hypertension, congestive heart failure and renal disease, and are considered relatively safe and generally well-tolerated drugs. However, adverse effects of ACEIs have been reported, including non-productive cough and angioedema, which can lead to poor adherence to therapy. The mechanisms by which ACEIs promote adverse effects are not fully elucidated, although increased bradykinin plasma levels following ACEI therapy seem to play an important role. Since bradykinin can sensitise the transient potential vanilloid receptor 1 (TRPV1), we investigated the role of TRPV1 in plasma extravasation in the trachea and bronchi of rats treated with the ACEI captopril. We observed that intravenous (i.v.) administration of captopril did not cause plasma extravasation in the trachea or bronchi of spontaneously breathing rats, but induced plasma extravasation in the trachea and bronchi of artificially ventilated rats. The intratracheal (i.t.) instillation of capsaicin or bradykinin also induced an increase in plasma extravasation in the trachea and bronchi of artificially ventilated rats. As expected, capsaicin-induced plasma extravasation was inhibited by i.t. pretreatment with the TRPV1 selective antagonist capsazepine (CPZ) while bradykinin-induced plasma extravasation was reduced by i.t. pretreatment with the selective B2 receptor antagonist Icatibant, originally known as HOE 140 (HOE). Interestingly, bradykinin-induced plasma extravasation was also inhibited by CPZ. The pretreatment with HOE and CPZ, singly or in combination and at doses which do not cause inhibitory effects per se, significantly inhibited the plasma extravasation induced by captopril treatment in artificially ventilated rats. In addition, treatment with a high dose of capsaicin in newborn rats, which induces degeneration of TRPV1-expressing sensory neurons, abolished both capsaicin and captopril-induced plasma extravasation in artificially ventilated rats. In conclusion, our study identified that captopril treatment promoted sensitisation of TRPV1, via B2 receptor activation, inducing plasma extravasation in the airways of mechanically ventilated rats. The present findings add a new view about the role of TRPV1 in the plasma extravasation induced by captopril and could to contribute to the elucidation of mechanisms by which ACEI induces adverse effects on airways.

Kinin receptors in skin wound healing.

BACKGROUND: Wound healing is a complex and dynamic process that includes 3 different phases: inflammation, proliferation, and remodeling. Kinins are vasoactive peptides released after tissue injury, and are directly involved in the development and maintenance of inflammatory processes, and their actions are mediated by the activation of receptors called B1 and B2. OBJECTIVE: We aimed to evaluate the involvement of kinin receptors in the skin healing process. METHODS: Knockout mice for kinin receptors (KOB1, KOB2 and KOB1B2) and wild type controls (WT) were subjected to a skin excision model, and tissue repair process was evaluated during different phases of wound healing. RESULTS: In knockout animals for kinin receptors differences were observed in the resolution period of injury exceeding 17 days for the total closure of wounds. The absence of kinin receptors promotes a significant reduction in infiltration of polymorphonuclear cells on day 2 of the inflammatory phase. Already at the late stage of this phase (3 days) there was a negative influence on the infiltration of polymorphonuclear and mononuclear cells at the site of injury in comparison to WT. Collagen was significantly diminished in tissue of KOB1, KOB2 and KOB1B2 from day two to the end of the healing process. Moreover, wound tissue from KOB2 and KOB1B2, but not KOB1, presented impaired parameters of re-epitheliazation, reduced proliferation of cells (PCNA immunostaining), and a lower number of myofibroblasts (α-SMA immunostaining). CONCLUSION: These data reveal the involvement of kinin receptors in processes of skin repair. Both kinin receptors participate especially during the inflammatory phase, while B2 receptors seem to be more relevant in the quality of the wound scar. Thus, a better understanding of the contribution of kinins to skin wound healing may reveal novel options for therapy.

Quantitative genotoxicity assays for analysis of medicinal plants: A systematic review.

ETHNOPHARMACOLOGICAL RELEVANCE: Medicinal plants are known to contain numerous biologically active compounds, and although they have proven pharmacological properties, they can cause harm, including DNA damage. AIM OF THE STUDY: Review the literature to evaluate the genotoxicity risk of medicinal plants, explore the genotoxicity assays most used and compare these to the current legal requirements. MATERIAL AND METHODS: A quantitative systematic review of the literature, using the keywords "medicinal plants", "genotoxicity" and "mutagenicity", was undertakenQ to identify the types of assays most used to assess genotoxicity, and to evaluate the genotoxicity potential of medicinal plant extracts. RESULTS: The database searches retrieved 2289 records, 458 of which met the inclusion criteria. Evaluation of the selected articles showed a total of 24 different assays used for an assessment of medicinal plant extract genotoxicity. More than a quarter of those studies (28.4%) reported positive results for genotoxicity. CONCLUSIONS: This review demonstrates that a range of genotoxicity assay methods are used to evaluate the genotoxicity potential of medicinal plant extracts. The most used methods are those recommended by regulatory agencies. However, based on the current findings, in order to conduct a thorough study concerning the possible genotoxic effects of a medicinal plant, we indicate that it is important always to include bacterial and mammalian tests, with at least one in vivo assay. Also, these tests should be capable of detecting outcomes that include mutation induction, clastogenic and aneugenic effects, and structural chromosome abnormalities. In addition, the considerable rate of positive results detected in this analysis further supports the relevance of assessing the genotoxicity potential of medicinal plants.

Inhibitory effect of GB-2a (I3-naringenin-II8-eriodictyol) on melanogenesis.

ETHNOPHARMACOLOGY RELEVANCE: GB-2a is a I3-naringenin-II8-eriodictyol compound isolated from Garcinia gardneriana (Planchon & Triana) Zappi, a plant used in folk medicine for the treatment of skin disorders. AIM OF STUDY: In the search for new depigmenting agents, this study was carried out to investigate the in vitro effects of GB-2a isolated from G. gardneriana (Planchon & Triana) Zappi in B16F10 melanoma cells. MATERIALS AND METHODS: The effects of GB-2a were evaluated through determination of melanin biosynthesis in B16F10 melanoma cells in comparison with the reference drug kojic acid (500µM). In parallel, the GB-2a effect was assessed in a cell viability assay. Mushroom tyrosinase activity assays were conducted to verify the effect of this enzyme. In order to ascertain the nature of enzyme inhibition on tyrosinase, kinetics analysis of the GB-2a was performed with L-tyrosine and L-3,4-dihydroxyphenylalanine (L-DOPA) substrates. RESULTS: The results showed that GB-2a biflavonoid significantly inhibited the melanin content, without reducing cell viability. GB-2a also showed a strong antityrosinase activity in the mushroom tyrosinase assay. GB-2a inhibited the tyrosinase activity, exerting a mixed inhibition. For the L-tyrosine substrate the inhibition was in non-competitive mode and for L-DOPA it was in uncompetitive mode. CONCLUSION: GB-2a biflavonoid promoted inhibition on tyrosinase activity and reduced melanin biosynthesis in B16F10 cells, which suggests great potential for medical and cosmetic uses as a depigmenting agent.

Investigation of anti-inflammatory and anti-proliferative activities promoted by photoactivated cationic porphyrin.

BACKGROUND: Photodynamic therapy (PDT) is a technique that uses light and a photosensitizer, converting local molecular oxygen into singlet oxygen, which eliminates a target unhealthy tissue. It has been increasingly used for the treatment of several diseases including skin disorders. Psoriasis is a chronic inflammatory skin disease expressing immune and hyperproliferative features. OBJECTIVE: This study aimed to evaluate the effect of the photosensitizer 5,10-diphenyl-15,20-di(N-methylpyridinium-4-yl)porphyrin (Di-cis-Py+) in in vivo models whereby some psoriasis-like parameters could be investigated. METHODS: The antiinflammation and antiproliferative activities of Di-cis-Py+ photoactivated was measured by myeloperoxidase (MPO) and N-acetyl-ß-d-glucosaminidase (NAG) enzyme activity assay, measurement of IL-6, IL-1ß and TNF-α levels, evaluation of proliferating cell nuclear antigen (PCNA) levels by immunohistochemistry and by Western blot. RESULTS: Treatment involving PDT and Di-cis-Py+ resulted in reduction of edema, cellular infiltration, proinflammatory cytokines, as well as reduced hyperproliferation of the epidermis. All the evaluated parameters were promoted by topical application of phlogistic agents and are similar to that observed in lesions of psoriatic skin. CONCLUSION: The results shows the advantage of topical application, do not cause apparently photosensitivity and have effects comparable to dexamethasone, a first-line drug for the treatment of the disease.

Combretum leprosum Mart. (Combretaceae): potential as an antiproliferative and anti-inflammatory agent.

ETHNOPHARMACOLOGICAL RELEVANCE: Combretum leprosum is a species that is popularly used in Brazil as a healing agent to treat skin problems and lesions. In this study we investigated the possible potential of this extract to treat inflammatory and hyperproliferative skin conditions. MATERIALS AND METHODS: Classical models of skin inflammation such as TPA- and croton oil-induced mouse ear oedema were applied in order to verify the potential topical anti-inflammatory activity of the ethanolic extract from flowers of Combretum leprosum. RESULTS: Topical application of ethanolic extract promoted a dose-dependent inhibition of phorbol ester-induced ear oedema, reduced myeloperoxidase activity and IL-6 tissue levels with inhibition comparable to dexamethasone (positive control). Histological and immunohistochemical analysis revealed that ethanolic extract also suppressed cell infiltration. Ethanolic extract altered inflammatory parameters on a chronic skin inflammation model induced by repeated applications of croton oil, decreasing ear oedema, epidermal hyperproliferation and cell infiltration. In addition, immunohistochemical analysis showed that the extract decreased PCNA expression on the epidermis. CONCLUSION: Taken together, these results suggest that the extract from flowers of Combretum leprosum could be considered as a new potential tool for the treatment of several skin inflammatory diseases since it reversed the skin inflammatory and hyperproliferative process in a very significant manner. Further investigations are needed in order to verify the cellular mechanism and safety of Combretum leprosum extract.

In vivo participation of nitric oxide in hyperproliferative epidermal phenomena in mice.

A significant involvement of nitric oxide (NO) in the process of keratinocyte proliferation is reported with many divergences. To determine the involvement of NO in the hyperproliferative process of epidermis in vivo, non-selective inhibitor (N(G)-nitro-L-arginine-methyl ester.HCl: L-NAME) and selective inhibitors for inducible NO synthase (iNOS) and neuronal NO synthase (nNOS) (Aminoguanidine: AG and 7-Nitroindazole: 7-NI, respectively) and a NO-donor (Sodium nitroprusside: SNP) were topically applied twice a day in mice ear treated with multiple applications of croton oil. L-NAME and 7-NI treatments decreased and SNP increased ear edema formation. However, ear weight was reduced in groups that received L-NAME and 7-NI, while the AG and SNP groups presented an increment. The histological evaluation of epidermis thickness showed that all NOS inhibitors were able to prevent the increase in epidermis width caused by croton oil, while SNP contributed to enlargement. The same results were observed in the PCNA staining, where treatments with NOS inhibitors caused a reduction in the number of cells in the epidermis, while SNP caused an enhancement. 7-NI treatment reduced polymorphonuclear and mononuclear leukocytes migration when compared to the control group. The AG application increased the migration of polymorphonuclear and mononuclear cells, while the SNP enhanced only the polymorphonuclear cells. Therefore, in the skin NO produced by nNOS is involved in the control of keratinocyte hyperproliferation, with the contribution of iNOS. In the animal model of cutaneous chronic inflammation by croton oil, NO is involved in the exudation and leukocyte migration, with participation of all three enzymes.

Simvastatin ointment, a new treatment for skin inflammatory conditions.

BACKGROUND: Statins represent a class of drugs that effectively lowers cholesterol, however they also possess pleiotropic effects, like promotion of angiogenesis, prevention of bone loss, immunomodulatory and anti-inflammatory effects. OBJECTIVES: Thus, the aim of this study was to investigate the activity of simvastatin topically applied in mice in acute and chronic skin inflammation models. METHODS: Skin inflammation was induced in mice ears by topical application of 12-O-tetradecanoylphorbol acetate (TPA). In the acute model, ear oedema was measured by the increase of ear thickness 6h after TPA (2.5µg/ear). The chronic inflammatory process was induced by multiple applications of TPA (2.0µg/ear) for nine alternate days, and the oedema was measured daily as the increase in ear thickness. RESULTS: Topical treatment was applied immediately after TPA in acute model or started at 5th day of chronic experiment. For acute model treatment was simvastatin (0.24, 0.71 and 2.40µM), dexamethasone (0.13µM), both in acetone or vehicle alone (acetone). In chronic model simvastatin (1% and 3%) and dexamethasone (0.5%) were incorporated in ointment preparations, and a group received ointment alone (vehicle). Samples of ear tissue (6mm) were taken from acute and chronic models, weighted and prepared for histological analysis and myeloperoxidase (MPO) enzymatic activity evaluation. Application of simvastatin in acetone reduced the ear oedema after a single TPA application in a dose dependent manner [ID(50) of 0.47 (0.22-1.13) µM], and the MPO enzymatic activity up to 61±10%. Also, both simvastatin ointment preparations 1% and 3% reduced acute TPA-induced ear oedema in 55±7% and 65±8%, respectively. In the chronic model, simvastatin ointment 1% was able to reduce ear oedema (25±3%) and ear weight (10±1%), though 3% formulation augmented both parameters. Histological analysis revealed a reduction of swelling and leukocyte migration in the acute model for both the formulations of simvastatin (1% and 3%), while in chronic model simvastatin 1% decreased ear swelling and epidermal thickness, but simvastatin 3% increased both parameters. CONCLUSION: The results confirm the anti-inflammatory activity of simvastatin when applied topically in both acute and chronic models of skin inflammation. Besides, the formulation of simvastatin ointment 1% shows to be a very effective formulation for a chronic usage.