Evaluation of a therapeutic concentration of dithranol in the mouse-tail test

Dithranol targets keratinocytes, their crosstalk with neutrophils and inhibits the IL-36 inflammatory loop in psoriasis

Despite the introduction of biologics, topical dithranol (anthralin) has remained one of the most effective anti-psoriatic agents. Serial biopsies from human psoriatic lesions and both the c-Jun/JunB and imiquimod psoriasis mouse model allowed us to study the therapeutic mechanism of this drug. Top differentially expressed genes in the early response to dithranol belonged to keratinocyte and epidermal differentiation pathways and IL-1 family members (i.e. IL36RN) but not elements of the IL-17/IL-23 axis. In human psoriatic response to dithranol, rapid decrease in expression of keratinocyte differentiation regulators (e.g. involucrin, SERPINB7 and SERPINB13), antimicrobial peptides (e.g. ß-defensins like DEFB4A, DEFB4B, DEFB103A, S100 proteins like S100A7, S100A12), chemotactic factors for neutrophils (e.g. CXCL5, CXCL8) and neutrophilic infiltration was followed with much delay by reduction in T cell infiltration. Targeting keratinocytes rather than immune cells may be an alternative approach in particular for topical anti-psoriatic treatment, an area with high need for new drugs.

Healing effect of Dillenia indica fruit extracts standardized to betulinic acid on ultraviolet radiation-induced psoriasis-like wounds in rats

CONTEXT

Dillenia indica Linn. (Dilleniaceae) is traditionally used to treat skin inflammation.

OBJECTIVE

This study evaluated the healing effect of Dillenia indica fruit extracts on induced psoriasis-like wounds in Wistar rats.

MATERIALS AND METHODS

Extracts were standardized to betulinic acid, including an aqueous ethanolic extract (AEE), ethyl acetate extract (EAE) and petroleum ether extract. Effects against lipid peroxidation were assessed in vitro. Wounds were created at rat tails (n = 12). Topical treatments were applied once daily for 7 days (1 mL of AEE or EAE at 5 or 50 mg/mL). Maximal dose was defined by the extract solubility. A 10-fold lower dose was also tested. Positive and negative controls were treated with clobetasol (0.5 mg/mL) or excipient. Half of each group was euthanized for histology. The remaining animals were observed for 20 days for wound measurements.

RESULTS

Yields of AEE and EAE were 4.3 and 0.7%, respectively. Betulinic acid concentrations in AEE and EAE were 4.6 and 107.6 mg/g. Extracts neutralized lipid peroxidation in vitro at 0.02 μg/mL, accelerating healing at 50 mg/mL. Complete healing in mice treated with AEE occurred 16 days after wound induction. This time was 14 and 12 days in mice treated with EAE and clobetasol. Compared to orthokeratosis, parakeratosis was reduced by AEE (25%), EAE (45%) and clobetasol (55%). EAE caused superior protection against biomolecules oxidation of skin compared to AEE.

DISCUSSION AND CONCLUSION

EAE exhibited activity closer to that of clobetasol. Betulinic acid may be an active constituent, which should be assessed in future studies.

Liposomal fusidic acid as a potential delivery system: a new paradigm in the treatment of chronic plaque psoriasis

Chronic plaque psoriasis is an inflammatory skin disease affecting 2-3% of the world population. With increasing understanding of the progress of disease and its causes, bacterial infection is reported to be one of the potential reasons. In this regard, fusidic acid (FA), a steroidal antibiotic, has been a drug of choice which could play an important role by virtue of its unique mechanism of action. Despite many topical formulations of FA in practice, drug-delivery issues like permeability in the prevailing infectious conditions and stability of the drug are yet the challenges not been covered so far from the formulation development perspective. For these issues, liposomes, on account of their carrier-specific properties, have been suggested as delivery tools to fulfill the expectations. In the present work, FA liposomes (FA-LP) were prepared and characterized for its varied traits such as size (420-740 nm), surface charge, morphology, percent skin permeation (>75%), and retention (1.620 ± 0.8 mg/cm(2)). Confocal laser scanning microscope (CLSM) images revealed appreciable cell-uptake of fluorescent dye-loaded liposomes. In stability, FA-LP proved to be stable with respect to drug leakage and vesicle size. In vivo studies using the mouse tail model, FA-LP, are found significantly better (p < 0.05) vis-à-vis conventional one with improved efficacy in and around the target site by the carrier-effect. Hence, the work suggests for the possibility of a better FA liposome-based formulation as a potential option in addressing the infectious challenges of psoriasis.

Antipsoriatic activity of extracts and fractions obtained from Memecylon malabaricum leaves

Objectives

This study involves the evaluation of Memecylon malabaricum Cogn. (Melastomataceae) leaves for antipsoriatic activity.

Methods

Aqueous extract, hydroalcoholic extract and their fractions of M. malabaricum leaves were evaluated for in-vivo antipsoriatic activity by mouse tail test and for in-vitro antipsoriatic activity using HaCaT cells, lipoxygenase inhibition and thymidine phosphorylase inhibition assays. Extracts and fractions were evaluated for total phenol and flavonoid contents. HPTLC was used for screening and fingerprint analysis of the extracts and active fraction.

Key findings

M. malabaricum hydroalcoholic extract (MMHA) and water fraction of MMHA (MMHAW) produced significant (P &lt; 0.05) percent orthokeratosis in the mouse tail test. All samples except MMHA showed a significant (P &lt; 0.05) reduction in epidermal thickness in the mouse tail test when compared with control. Maximum activity against HaCaT cells was shown by chloroform fraction of MMHA (MMHAC). The M. malabaricum decoction (MMD) and water fraction of MMD (MMDW) showed equally good inhibition of lipoxygenase. In thymidine phosphorylase inhibition assay only MMD showed activity.

Conclusions

The findings of this investigation reveal that the leaves of M. malabaricum have good antipsoriatic potential, which provides scope for further detailed research in to this plant for psoriasis.

Ethyl acetate fraction of the root of Rubia cordifolia L. inhibits keratinocyte proliferation in vitro and promotes keratinocyte differentiation in vivo: potential application for psoriasis treatment

Psoriasis is a skin disease associated with hyperproliferation and aberrant differentiation of keratinocytes. Our previous studies have identified the root of Rubia cordifolia L. as a potent antiproliferative and apoptogenic agent in cultured HaCaT cells (IC(50) 1.4 microg/ml). In the present study, ethanolic extract of Radix Rubiae was fractioned sequentially with hexane, ethyl acetate (EA), n-butanol and water. EA fraction was found to possess most potent antiproliferative action on HaCaT cells (IC(50) 0.9 microg/ml). Mechanistic study revealed that EA fraction induced apoptosis on HaCaT cells, as it was capable of inducing apoptotic morphological changes. Annexin V-PI staining assay also demonstrated that EA fraction significantly augmented HaCaT apoptosis. In addition, EA fraction decreased mitochondrial membrane potential in a concentration- and time-dependent manner. The standardized EA fraction was formulated into topical gel and its keratinocyte-modulating action was tested on mouse tail model. EA fraction dose-dependently increased the number and thickness of granular layer and epidermal thickness on mouse tail skin, indicative of the keratinocyte differentiation-inducing activity. Taking the in vitro and in vivo findings together, the present preclinical study confirms that EA fraction is a promising antipsoriatic agent warranting further development for psoriasis treatment.

Determination of epidermal proliferative activity in experimental mouse tail test by AgNOR analysis

Nucleolar organizer regions are segments of DNA coding ribosomal genes, which can be histologically detected by silver technique as so-called AgNORs. The estimation of AgNOR number and AgNOR size are currently under investigation as markers of cellular proliferation activity. We therefore examined the epidermal AgNOR expression after topical application of different antiproliferative compounds using the mouse tail test. The epidermis of 0.025% fluocinolone acetonide-treated mouse tails had the lowest AgNOR expression. Pretreatment with 0.2% Anthralin, 1% propyl gallate and 2% 3,4-hexaalkylbenzoylacrylic acid, an experimental phospholipase-A2 inhibitor, also revealed significant inhibition effects of epidermal AgNOR expression. Native and petrolatum-treated epidermis as control showed the highest AgNOR expression. The AgNOR results in basal cells proved to be more informative than these in the stratum spinosum, the best parameter was the AgNOR number. The obtained results were closely related to the values of the corresponding studies of PCNA expression. The AgNOR method seems to be useful for estimation of antiproliferative efficiency of pharmacological substances. This technique is simple in handling and can be applied using paraffin-embedded tissue sections.