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Alves LDF, Moore JB, Kell DB. The Biology and Biochemistry of Kynurenic Acid, a Potential Nutraceutical with Multiple Biological Effects. Int J Mol Sci 2024; 25:9082. [PMID: 39201768 PMCID: PMC11354673 DOI: 10.3390/ijms25169082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2024] [Revised: 08/16/2024] [Accepted: 08/19/2024] [Indexed: 09/03/2024] Open
Abstract
Kynurenic acid (KYNA) is an antioxidant degradation product of tryptophan that has been shown to have a variety of cytoprotective, neuroprotective and neuronal signalling properties. However, mammalian transporters and receptors display micromolar binding constants; these are consistent with its typically micromolar tissue concentrations but far above its serum/plasma concentration (normally tens of nanomolar), suggesting large gaps in our knowledge of its transport and mechanisms of action, in that the main influx transporters characterized to date are equilibrative, not concentrative. In addition, it is a substrate of a known anion efflux pump (ABCC4), whose in vivo activity is largely unknown. Exogeneous addition of L-tryptophan or L-kynurenine leads to the production of KYNA but also to that of many other co-metabolites (including some such as 3-hydroxy-L-kynurenine and quinolinic acid that may be toxic). With the exception of chestnut honey, KYNA exists at relatively low levels in natural foodstuffs. However, its bioavailability is reasonable, and as the terminal element of an irreversible reaction of most tryptophan degradation pathways, it might be added exogenously without disturbing upstream metabolism significantly. Many examples, which we review, show that it has valuable bioactivity. Given the above, we review its potential utility as a nutraceutical, finding it significantly worthy of further study and development.
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Affiliation(s)
- Luana de Fátima Alves
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Søltofts Plads, 2800 Kongens Lyngby, Denmark
| | - J. Bernadette Moore
- School of Food Science & Nutrition, University of Leeds, Leeds LS2 9JT, UK;
- Department of Biochemistry, Cell & Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St., Liverpool L69 7ZB, UK
| | - Douglas B. Kell
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Søltofts Plads, 2800 Kongens Lyngby, Denmark
- Department of Biochemistry, Cell & Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St., Liverpool L69 7ZB, UK
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Zatloukalova M, Hanyk J, Papouskova B, Kabelac M, Vostalova J, Vacek J. Tapinarof and its structure-activity relationship for redox chemistry and phototoxicity on human skin keratinocytes. Free Radic Biol Med 2024; 223:212-223. [PMID: 39067626 DOI: 10.1016/j.freeradbiomed.2024.07.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 07/08/2024] [Accepted: 07/25/2024] [Indexed: 07/30/2024]
Abstract
Tapinarof (3,5-dihydroxy-4-isopropylstilbene) is a therapeutic agent used in the treatment of psoriasis (VTAMA®). In this study, we examined the redox behaviour, (photo)stability, (photo)toxicity and (bio)transformation of tapinarof in the context of a structure-activity relationship study. Selected derivatives of the structurally related tapinarof were investigated, namely resveratrol, pterostilbene, pinosylvin and its methyl ether. Tapinarof undergoes electrochemical oxidation in a neutral aqueous medium at a potential of around +0.5 V (vs. Ag|AgCl|3M KCl). The anodic reaction of this substance is a proton-dependent irreversible and adsorption-driven process. The pKa value of tapinarof corresponds to 9.19 or 9.93, based on empirical and QM calculation approach, respectively. The oxidation potentials of tapinarof and its analogues correlate well with their HOMO (highest occupied molecular orbital) energy level. The ability to scavenge the DPPH radical decreased in the order trolox ≥ resveratrol > pterostilbene > tapinarof > pinosylvin ≫ pinosylvin methyl ether. It was also confirmed that tapinarof, being a moderate electron donor, is able to scavenge the ABTS radical and inhibit lipid peroxidation. The 4'-OH group plays a pivotal role in antioxidant action of stilbenols. During the stability studies, it was shown that tapinarof is subject to spontaneous degradation under aqueous conditions, and its degradation is accelerated at elevated temperatures and after exposure to UVA (315-399 nm) radiation. In aqueous media at pH 7.4, we observed an ∼50 % degradation of tapinarof after 48 h at laboratory temperature. The main UVA photodegradation processes include dihydroxylation and hydration. In conclusion, the phototoxic effect of tapinarof on a human keratinocytes cell line (HaCaT) was evaluated. Tapinarof exhibited a clear phototoxic effect, similar to phototoxic standard chlorpromazine. The IC50 values of the cytotoxicity and phototoxic effects of tapinarof correspond to 27.6 and 3.7 μM, respectively. The main HaCaT biotransformation products of tapinarof are sulfates and glucuronides.
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Affiliation(s)
- Martina Zatloukalova
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hněvotínská 3, 775 15, Olomouc, Czech Republic
| | - Jiri Hanyk
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hněvotínská 3, 775 15, Olomouc, Czech Republic
| | - Barbora Papouskova
- Department of Analytical Chemistry, Faculty of Science, Palacky University, 17. Listopadu 12, 771 46, Olomouc, Czech Republic
| | - Martin Kabelac
- Department of Chemistry, Faculty of Science, University of South Bohemia, Branišovská 31, České Budějovice, 370 05, Czech Republic
| | - Jitka Vostalova
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hněvotínská 3, 775 15, Olomouc, Czech Republic
| | - Jan Vacek
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hněvotínská 3, 775 15, Olomouc, Czech Republic.
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Pender EK, Kirby B. An update on topical therapies for psoriasis. Curr Opin Rheumatol 2024; 36:289-294. [PMID: 38651512 DOI: 10.1097/bor.0000000000001018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
PURPOSE OF REVIEW Topical therapies are a mainstay of treatment for mild psoriasis and may be a useful adjunct in treatment of moderate-to-severe psoriasis. This review summarizes recent advances in topical therapies for psoriasis and currently available treatments. RECENT FINDINGS Topical aryl hydrocarbon receptor modulators (tapinarof) and topical phosphodiesterase-4 inhibitors (roflumilast) have been proven effective in randomized controlled trials for psoriasis. Although topical JAK inhibitors have also been studied, none are currently licensed for treatment of psoriasis. Topical corticosteroids and vitamin D analogues remain the most commonly used and widely available topical treatments for psoriasis. Cost may limit use of novel topical agents. SUMMARY Although the novel topical agents tapinarof and roflumilast are licensed for treatment of psoriasis by the FDA in the United States, they have not yet been licensed in Europe, and it remains to be seen whether they will be limited by cost.
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Affiliation(s)
| | - Brian Kirby
- St Vincent's University Hospital, Elm Park
- Charles Institute of Dermatology, University College Dublin, Belfield, Dublin 4, Ireland
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Cao XC, Lu JW, Feng YF, Song LB, Lu Y. Efficacy and safety of Ruxolitinib, Crisaborole, and Tapinarof for mild-to-moderate atopic dermatitis: a Bayesian network analysis of RCTs. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:4657-4662. [PMID: 38358466 DOI: 10.1007/s00210-024-02971-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024]
Abstract
Given the lack of head-to-head studies of novel non-steroidal molecule topical therapies in mild-to-moderate atopic dermatitis (AD), network meta-analyses (NMAs) can provide comparative efficacy and safety data for clinical decision-making. In this NMA, we performed a literature search until 01 March 2023 for eligible studies written in English using databases, including PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov. Only double-blind randomized clinical trials (RCTs) with topical Ruxolitinib, Crisaborole, or Tapinarof versus vehicle for patients with mild-to-moderate AD were included. Baseline and follow-up data were extracted. Efficacy was evaluated using Investigator's Global Assessment (IGA) achieving "clear" or "almost clear," with 2 points or more improvement from baseline at the end of treatment, referred to as "IGA success." For binary outcomes, we analyzed in random-effects Bayesian NMA consistency models to compare the efficacy of these 3 topical therapies by odds ratio (OR) with 95% credibility interval (CrI). Overall, 10 phase 2 or phase 3 RCTs were identified, which included 4010 patients with mild to moderate AD. Compared with the topical vehicle control, all these 3 treatments had higher response rate of "IGA success" at the end of trial (Ruxolitinib 1.5% b.i.d: OR, 11.94; 95%CrI, 6.28-23.15; Crisaborole 2% b.i.d: OR, 2.08; 95%CrI, 1.46-3.52; Tapinarof 1% b.i.d: OR, 2.64; 95%CrI, 0.75-9.70). Notably, Ruxolitinib 1.5% b.i.d. had the highest probability of achieving "IGA success" in ranking analysis (Rank 1, SUCRA = 0.75) and lower risk of AE (Rank 8, SUCRA = 0.22). Besides, there was no difference in treatment-related adverse events between 3 therapies. Heterogeneity was not significant across studies.
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Affiliation(s)
- Xue-Chen Cao
- Department of Dermatology, Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital, Nanjing, 210029, China
| | - Jia-Wei Lu
- Department of Dermatology, Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital, Nanjing, 210029, China
| | - Yi-Fei Feng
- Department of Dermatology, Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital, Nanjing, 210029, China
| | - Le-Bin Song
- Department of Dermatology, Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital, Nanjing, 210029, China
| | - Yan Lu
- Department of Dermatology, Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital, Nanjing, 210029, China.
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Silverberg JI, Boguniewicz M, Quintana FJ, Clark RA, Gross L, Hirano I, Tallman AM, Brown PM, Fredericks D, Rubenstein DS, McHale KA. Tapinarof validates the aryl hydrocarbon receptor as a therapeutic target: A clinical review. J Allergy Clin Immunol 2024; 154:1-10. [PMID: 38154665 DOI: 10.1016/j.jaci.2023.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/09/2023] [Accepted: 12/08/2023] [Indexed: 12/30/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that has wide-ranging roles, including regulation of inflammation and homeostasis. AhR is not a cell surface receptor; rather, it exists in a cytoplasmic complex that responds to a wide variety of structurally dissimilar endogenous, microbial, and environmental ligands. The ubiquitous expression of AhR, its ability to be activated by a wide range of ligands, and its capacity to act as a master regulator for gene expression and homeostasis make it a promising new therapeutic target. Clinical trials of tapinarof cream have now validated AhR agonism as a therapeutic approach that can deliver significant efficacy for treating inflammatory skin diseases, including psoriasis and atopic dermatitis. Tapinarof 1% cream is a first-in-class, nonsteroidal, topical, AhR agonist with a pharmacokinetic profile that results in localized exposure at sites of disease, avoiding systemic safety concerns, drug interactions, or off-target effects. Psoriasis and atopic dermatitis both involve epidermal inflammation, cellular immune responses, dysregulation of skin barrier protein expression, and oxidative stress. On the basis of the clinical effectiveness of tapinarof cream for treating inflammatory skin diseases, we review how targeting AhR may offer a significant opportunity in other conditions that share key aspects of pathogenesis, including asthma, inflammatory bowel disease, eosinophilic esophagitis, ophthalmic, and nervous system diseases.
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Affiliation(s)
| | - Mark Boguniewicz
- Division of Allergy-Immunology, Department of Pediatrics, National Jewish Health and University of Colorado School of Medicine, Denver, Colo
| | - Francisco J Quintana
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass
| | | | - Lara Gross
- Dallas Allergy and Asthma Center, and the Allergy and Immunology Division, Baylor University Medical Center, Dallas, Tex
| | - Ikuo Hirano
- Northwestern University Feinberg School of Medicine, Chicago, Ill
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Stefanovic N, Irvine AD. Filaggrin and beyond: New insights into the skin barrier in atopic dermatitis and allergic diseases, from genetics to therapeutic perspectives. Ann Allergy Asthma Immunol 2024; 132:187-195. [PMID: 37758055 DOI: 10.1016/j.anai.2023.09.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/22/2023] [Accepted: 09/19/2023] [Indexed: 10/03/2023]
Abstract
Atopic dermatitis (AD) is the most common inflammatory skin disease worldwide, affecting 20% of children and 5% of adults. One critical component in the pathophysiology of AD is the epidermal skin barrier, with its outermost layer, the stratum corneum (SC), conferring biochemical properties that enable resilience against environmental threats and maintain homeostasis. The skin barrier may be conceptualized as a key facilitator of complex interactions between genetics, host immunity, the cutaneous microbiome, and environmental exposures. The key genetic risk factor for AD development and persistence is a loss-of-function mutation in FLG, with recent advances in genomics focusing on rare variant discovery, establishment of pathogenic mechanisms, and exploration of the role of other epidermal differentiation complex gene variants in AD. Aberrant type 2 inflammatory responses down-regulate the transcription of key epidermal barrier genes, alter the composition of SC lipids, and induce further injury through a neurocutaneous feedback loop and the itch-scratch cycle. The dysbiotic epidermis exhibits reduced bacterial diversity and enhanced colonization with Staphylococcus and Malassezia species, which contribute to both direct barrier injury through the action of bacterial toxins and perpetuation of the inflammatory cascades. Enhanced understanding of each of the pathogenic mechanisms underpinning barrier disruption has led to the development of novel topical and systemic molecules, including interleukin (IL)-4Ra, IL-13, PDE4, and Janus-associated kinase inhibitors, whose clinical effectiveness exceeds conventional treatment modalities. In this narrative review, we aim to summarize the current understanding of the above-mentioned pathophysiological and therapeutic mechanisms, with a focus on the genetic, cellular, and molecular mechanisms underpinning AD development.
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Affiliation(s)
| | - Alan D Irvine
- Clinical Medicine, Trinity College Dublin, Dublin, Ireland.
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Caffarelli C, Giannetti A, Giannì G, Ricci G. Anti-inflammatory and biologic drugs for atopic dermatitis: a therapeutic approach in children and adolescents. Front Med (Lausanne) 2023; 10:1214963. [PMID: 37654660 PMCID: PMC10466416 DOI: 10.3389/fmed.2023.1214963] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 07/27/2023] [Indexed: 09/02/2023] Open
Abstract
Atopic dermatitis (AD) is a chronic inflammatory disease with a heterogeneous pathogenesis correlated with dysregulation of the immune system and a prevalence of the T2-mediated immune pathway. Recent understanding of the pathogenesis of AD has allowed the development of new drugs targeting different mechanisms and cytokines that have changed the treatment approach. The aim of this review is to update knowledge on the standard of care and recent advancements in the control of skin inflammation. In light of recent guidelines, we report on the clinical efficacy of novel treatments, with special attention to situations where biologics and small molecules are involved.
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Affiliation(s)
- Carlo Caffarelli
- Clinica Pediatrica, Azienda Ospedaliero-Universitaria, Department of Medicine and Surgery, Università di Parma, Parma, Italy
| | - Arianna Giannetti
- Paediatrics Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Giuliana Giannì
- Clinica Pediatrica, Azienda Ospedaliero-Universitaria, Department of Medicine and Surgery, Università di Parma, Parma, Italy
| | - Giampaolo Ricci
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
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Aoki V, Orfali RL. Aryl-hydrocarbon receptor agonist: A novel topical therapeutic approach for inflammatory skin diseases. J Eur Acad Dermatol Venereol 2023; 37:1093-1094. [PMID: 37171290 DOI: 10.1111/jdv.19080] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 03/27/2023] [Indexed: 05/13/2023]
Affiliation(s)
- Valeria Aoki
- Department of Dermatology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Raquel Leão Orfali
- Department of Dermatology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
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