Therapeutic and Cytotoxic Effects of the Novel Antipsoriasis Codrug, Naproxyl–Dithranol, on HaCaT Cells

An Innovative Fluid Dynamic System to Model Inflammation in Human Skin Explants

Skin is a major administration route for drugs, and all transdermal formulations must be tested for their capability to overcome the cutaneous barrier. Therefore, developing highly reliable skin models is crucial for preclinical studies. The current in vitro models are unable to replicate the living skin in all its complexity; thus, to date, excised human skin is considered the gold standard for in vitro permeation studies. However, skin explants have a limited life span. In an attempt to overcome this problem, we used an innovative bioreactor that allowed us to achieve good structural and functional preservation in vitro of explanted human skin for up to 72 h. This device was then used to set up an in vitro inflammatory model by applying two distinct agents mimicking either exogenous or endogenous stimuli: i.e., dithranol, inducing the contact dermatitis phenotype, and the substance P, mimicking neurogenic inflammation. Our in vitro system proved to reproduce inflammatory events observed in vivo, such as vasodilation, increased number of macrophages and mast cells, and increased cytokine secretion. This bioreactor-based system may therefore be suitably and reliably used to simulate in vitro human skin inflammation and may be foreseen as a promising tool to test the efficacy of drugs and cosmetics.

Novel Synergistic Approach: Tazarotene-Calcipotriol-Loaded-PVA/PVP-Nanofibers Incorporated in Hydrogel Film for Management and Treatment of Psoriasis

Psoriasis is an autoimmune skin disease that generally affects 1%-3% of the total population globally. Effective treatment of psoriasis is limited because of numerous factors, such as ineffective drug delivery and efficacy following conventional pharmaceutical treatments. Nanofibers are widely being used as nanocarriers for effective treatment because of their multifunctional and distinctive properties, including a greater surface area, higher volume ratio, increased elasticity and improved stiffness and resistance to traction, favorable biodegradability, high permeability, and sufficient oxygen supply, which help maintain the moisture content of the skin and improve the bioavailability of the drugs. Similar to the extracellular matrix, nanofibers have a regeneration capacity, promoting cell growth, adhesion, and proliferation, and also have a more controlled release pattern compared with that of other conventional therapies at the psoriatic site. To ensure improved drug targeting and better antipsoriatic efficacy, this study formulated and evaluated a tazarotene (TZT)-calcipotriol (CPT)-loaded nanofiber and carbopol-based hydrogel film. The nanofiber was prepared using electrospinning with a polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) K-90 polymeric blend that was later incorporated into a carbopol base to form hydrogel films. The prepared nanofibers were biochemically evaluated and in vitro and in vivo characterized. The mean diameters of the optimized formulation, i.e., TZT-loaded polyvinyl alcohol/polyvinylpyrrolidone nanofiber (TZT-PVA/PVP-NF) and TZT-CPT-loaded polyvinyl alcohol/polyvinylpyrrolidone nanofiber (TZT-CPT-PVA/PVP-NF) were 244.67 ± 58.11 and 252.31 ± 35.50 nm, respectively, as determined by scanning electron microscopy, and their tensile strength ranged from 14.02 ± 0.54 to 22.50 ± 0.03 MPa. X-ray diffraction revealed an increase in the amorphous nature of the nanofibers. The biodegradability studies of prepared nanofiber formulations, irrespective of their composition, showed that these completely biodegraded within 2 weeks of their application. The TZT-CPT-PVA/PVP-NF nanofibers exhibited 95.68% ± 0.03% drug release at the end of 72 h, indicating a controlled release pattern and following Higuchi release kinetics as a best-fit model. MTT assay, antioxidant and lipid profile tests, splenomegaly assessment, and weight fluctuation were all performed in the in vitro as well as in vivo studies. We found that the TZT-CPT-PVA/PVP-NF-based hydrogel film has high potential for antipsoriatic activity in imiquimod-induced Wistar rats in comparison with that of TT-PVA/PVP-NF nanofibers.

A Novel Curcumin-Mycophenolic Acid Conjugate Inhibited Hyperproliferation of Tumor Necrosis Factor-Alpha-Induced Human Keratinocyte Cells

Curcumin (CUR) has been used as adjuvant therapy for therapeutic application in the treatment of psoriasis through several mechanisms of action. Due to the poor oral bioavailability of CUR, several approaches have been developed to overcome the limitations of CUR, including the prodrug strategy. In this study, CUR was esterified with mycophenolic acid (MPA) as a novel conjugate prodrug. The MPA-CUR conjugate was structurally elucidated using FT-IR, ¹H-NMR, ¹³C-NMR, and MS techniques. Bioavailable fractions (BFs) across Caco-2 cells of CUR, MPA, and MPA-CUR were collected for further biological activity evaluation representing an in vitro cellular transport model for oral administration. The antipsoriatic effect of the BFs was determined using antiproliferation and anti-inflammation assays against hyperproliferation of tumor necrosis factor-alpha (TNF-α)-induced human keratinocytes (HaCaT). The BF of MPA-CUR provided better antiproliferation than that of CUR (p < 0.001). The enhanced hyperproliferation suppression of the BF of MPA-CUR resulted from the reduction of several inflammatory cytokines, including IL-6, IL-8, and IL-1β. The molecular mechanisms of anti-inflammatory activity were mediated by an attenuated signaling cascade of MAPKs protein, i.e., p38, ERK, and JNK. Our results present evidence for the MPA-CUR conjugate as a promising therapeutic agent for treating psoriasis by antiproliferative and anti-inflammatory actions.

Studies on the anti-psoriasis effects and its mechanism of a dual JAK2/FLT3 inhibitor flonoltinib maleate

Psoriasis is a chronic, inflammatory autoimmune disease mediated by T cells, and characterized with abnormal proliferation and differentiation of keratinocytes, and inflammatory infiltration. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway has been identified to play essential roles in mediating various of biological processes, and is closely related to autoimmune diseases. Dendritic cells (DCs) are important antigen presenting cells and play an important regulatory role in T cells. The proliferation, differentiation and function of DCs are regulated by JAK and FMS-like tyrosine kinase 3 (FLT3) signal pathways. Flonoltinib maleate (FM), a high selectivity dual JAK2/FLT3 inhibitor with IC50 values of 0.8 nM and 15 nM for JAK2 and FLT3, respectively, was developed by our laboratory. Moreover, FM was a potent JAK2 inhibitor with 863-fold and 696-fold selectivity over JAK1 and JAK3, respectively. In this study, the anti-psoriasis activity of FM was evaluated both in vitro and in vivo. FM effectively inhibited the proliferation of HaCaT, the inflammatory keratinocyte induced by M5 and markedly suppressed the generation and differentiation of DCs from bone marrow (BM), and inhibited the expression of FLT3 in DCs in vitro. FM effectively inhibited the ear thickening and improved the pathological changes of the ear in interleukin (IL)-23-induced psoriasis-like acanthosis mouse model. Further in keratin 14-vascular endothelial growth factor (K14-VEGF) transgenic homozygous mice model, FM could obviously improve the psoriatic symptom and pathological changes, significantly inhibit the generations of Th1 and Th17 cells in the spleen, and the accumulations of DCs in the ears. FM could also significantly reduce the expression of various inflammatory factors both in C57BL/6 and K14-VEGF mice ears, and the serum of K14-VEGF mice. Mechanism revealed that FM effectively suppressed the phosphorylation of JAK2, STAT3 and STAT5 in inflammatory keratinocytes and the mice ears of C57BL/6 and K14-VEGF, as well as the phosphorylation of FLT3 in K14-VEGF mice ears. In conclusion, FM plays an excellent anti-psoriasis activity, including inhibiting keratinocyte proliferation and regulating inflammatory response through inhibiting JAK2 and FLT3 signaling pathway.

An ex vivo skin model to probe modulation of local cutaneous arachidonic acid inflammation pathway

There is a need for inexpensive and reliable means to determine the modulation of cutaneous inflammation. The method outlined in this article draws together a number of scientific techniques and makes use of generally unwanted biological tissues as a means of determining skin inflammation ex vivo, and focuses on probing aspects of the arachidonic acid inflammation pathway. Freshly excised skin contains elevated levels of short-lived inducible cyclooxygenase-2 (COX-2) and, under viable conditions, COX-2 and its eicosanoid products will continue to be produced until tissue necrosis, providing a window of time in which relative levels can be probed to determine exacerbation due to an upregulating factor or downregulation due the presence of an agent exerting anti-inflammatory activity. Ex vivo porcine skin, mounted in Franz diffusion cells, is dosed topically with the xenobiotic challenge and then techniques such as Western blotting and immunohistochemistry can then be used to probe relative COX-2 levels on a semi-quantitative or qualitative level. Enzyme-linked immunosorbent assay or LCMS can be used to determine relative prostaglandin E-2 (PGE-2) levels. Thus far, the technique has been used to examine the effects of topically applied anti-inflammatories (betamethasone, ibuprofen, ketoprofen and methotrexate), natural products (fish oil, Devil’s claw extract and pomegranate rind extract) and drug delivery vehicle (polyNIPAM nanogels). Topically applied xenobiotics that modulate factors such as COX-2 and PGE-2 must penetrate the intact skin, and this provides direct evidence of overcoming the "barrier function" of the stratum corneum in order to target the viable epidermis in sufficient levels to be able to elicit such effects. This system has particular potential as a pre-clinical screening tool for those working on the development of topical delivery systems, and has the additional advantage of being in line with 3 Rs philosophy.

Methacrylated chitosan as a polymer with enhanced mucoadhesive properties for transmucosal drug delivery

Chitosan is a cationic polysaccharide that exhibits mucoadhesive properties which allow it to adhere to mucosal tissues. In this work, we explored chemical modification of chitosan through its reaction with methacrylic anhydride to synthesise methacrylated derivative with the aim to improve its mucoadhesive properties. The reaction products were characterised using ¹H NMR, FTIR and UV-Vis spectroscopy. ¹H NMR and ninhydrin test were used to quantify the degree of methacrylation of chitosan. Turbidimetric analysis of the effect of pH on aqueous solubility of the polymers revealed that the highly methacrylated derivative remained turbid and its turbidity did not change from pH 3 to 9. However, solutions of native chitosan and its derivative with low methacrylation remained transparent at pH 6.5 and exhibited a rapid increase in turbidity at pH > 6.5. The mucoadhesive properties of chitosan and its methacrylated derivatives were evaluated using flow-through method combined with fluorescent microscopy with fluorescein sodium as a model drug. The retention of these polymers was evaluated on porcine bladder mucosa in vitro. The methacrylated derivatives exhibited greater ability to retain fluorescein sodium on the bladder mucosa compared to the parent chitosan. Toxicological studies using MTT assay with UMUC3 bladder cells show no significant differences in toxicity between chitosan and its methacrylated derivatives suggesting good biocompatibility of these novel mucoadhesive polymers.

Biguanide Iridium(III) Complexes with Potent Antimicrobial Activity

We have synthesized novel organoiridium(III) antimicrobial complexes containing a chelated biguanide, including the antidiabetic drug metformin. These 16- and 18-electron complexes were characterized by NMR, ESI-MS, elemental analysis, and X-ray crystallography. Several of these complexes exhibit potent activity against Gram-negative bacteria and Gram-positive bacteria (including methicillin-resistant Staphylococcus aureus (MRSA)) and high antifungal potency toward C. albicans and C. neoformans, with minimum inhibitory concentrations (MICs) in the nanomolar range. Importantly, the complexes exhibit low cytotoxicity toward mammalian cells, indicating high selectivity. They are highly stable in broth medium, with a low tendency to generate resistance mutations. On coadministration, they can restore the activity of vancomycin against vancomycin-resistant Enterococci (VRE). Also the complexes can disrupt and eradicate bacteria in mature biofilms. Investigations of reactions with biomolecules suggest that these organometallic complexes deliver active biguanides into microorganisms, whereas the biguanides themselves are inactive when administered alone.

Anthralin modulates the expression pattern of cytokeratins and antimicrobial peptides by psoriatic keratinocytes

BACKGROUND

Psoriasis is an inflammatory skin disease with aberrant keratinocyte proliferation, presumably as a result of immune cell activation. Th17 cytokines like IL-17A and IL-22 are critically implicated in epidermal thickening, altered keratinocyte differentiation and production of innate factors such as antimicrobial peptides. Psoriasis treatment options include modern targeted therapies using anti-cytokine antibodies and traditional non-targeted treatments like anthralin (dithranol). While the mode of action of anti-cytokine antibodies is defined, the effects of topical anthralin on psoriatic skin are not fully understood.

OBJECTIVE

This study aims to unravel the direct effects of anthralin on keratinocyte proliferation, differentiation and production of psoriasis-associated factors.

METHODS

We tested the effects of anthralin on cell proliferation, cytokeratin expression and changes in the expression of antimicrobial peptides using primary keratinocytes and 3D psoriasis tissue models with and without stimulation of the psoriasis-promoting cytokines IL-17A and IL-22. Moreover, we compared the findings derived from monolayer and multilayer cultures to data derived from lesional skin of patients with psoriasis before and under treatment with anthralin.

RESULTS

Our study shows that anthralin directly induces cell apoptosis in vitro in monolayer cultures but not in 3D psoriasis tissue models treated with IL-17A and IL-22. Yet, keratinocyte proliferation as determined by Ki-67 staining is impaired by anthralin in vivo. In lesional skin but not in 3D psoriasis tissue models anthralin rapidly normalizes cytokeratin (CK)16 expression. Furthermore, anthralin directly inhibits DEFB4 expression in vitro and in vivo, while other antimicrobial peptides and cytokines studied like IL-6 and IL-8 are regulated differently in vitro and in vivo.

CONCLUSIONS

Our results show that anthralin directly regulates DEFB4A expression. However, its beneficial effects on psoriasis cannot be explained by direct effects on keratinocyte differentiation or cytokine expression.

Design, synthesis and in vitro degradation of a novel co-drug for the treatment of psoriasis

Psoriasis is a common, chronic and relapsing inflammatory skin disease. It affects approximately 2% of the western population and has no cure. Combination therapy for psoriasis often proves more efficacious and better tolerated than monotherapy with a single drug. Combination therapy could be administered in the form of a co-drug, where two or more therapeutic compounds active against the same condition are linked by a cleavable covalent bond. Similar to the pro-drug approach, the liberation of parent moieties post-administration, by enzymatic and/or chemical mechanisms, is a pre-requisite for effective treatment. In this study, a series of co-drugs incorporating dithranol in combination with one of several non-steroidal anti-inflammatory drugs, both useful for the treatment of psoriasis, were designed, synthesized and evaluated. An ester co-drug comprising dithranol and naproxen in a 1:1 stoichiometric ratio was determined to possess the optimal physicochemical properties for topical delivery. The co-drug was fully hydrolyzed in vitro by porcine liver esterase within four hours. When incubated with homogenized porcine skin, 9.5% of the parent compounds were liberated after 24 h, suggesting in situ esterase-mediated cleavage of the co-drug would occur within the skin. The kinetics of the reaction revealed first order kinetics, Vmax = 10.3 μM·min-1 and Km = 65.1 μM. The co-drug contains a modified dithranol chromophore that was just 37% of the absorbance of dithranol at 375 nm and suggests reduced skin/clothes staining. Overall, these findings suggest that the dithranol-naproxen co-drug offers an attractive, novel approach for the treatment of psoriasis.