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Paus R, Sevilla A, Grichnik JM. Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers. J Invest Dermatol 2024; 144:474-491. [PMID: 38099887 DOI: 10.1016/j.jid.2023.09.276] [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: 06/20/2023] [Revised: 08/09/2023] [Accepted: 09/12/2023] [Indexed: 02/25/2024]
Abstract
Hair graying holds psychosocial importance and serves as an excellent model for studying human pigmentation and aging in an accessible miniorgan. Current evidence suggests that graying results from an interindividually varying mixture of cumulative oxidative and DNA damage, excessive mTORC1 activity, melanocyte senescence, and inadequate production of pigmentation-promoting factors in the hair matrix. Various regulators modulate this process, including genetic factors (DNA repair defects and IRF4 sequence variation, peripheral clock genes, P-cadherin signaling, neuromediators, HGF, KIT ligand secretion, and autophagic flux. This leads to reduced MITF- and tyrosinase-controlled melanogenesis, defective melanosome transfer to precortical matrix keratinocytes, and eventual depletion of hair follicle (HF) pigmentary unit (HFPU) melanocytes and their local progenitors. Graying becomes irreversible only when bulge melanocyte stem cells are also depleted, occurring later in this process. Distinct pigmentary microenvironments are created as the HF cycles: early anagen is the most conducive phase for melanocytic reintegration and activation, and only during anagen can the phenotype of hair graying and repigmentation manifest, whereas the HFPU disassembles during catagen. The temporary reversibility of graying is highlighted by several drugs and hormones that induce repigmentation, indicating potential target pathways. We advise caution in directly applying mouse model concepts, define major open questions, and discuss future human antigraying strategies.
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Affiliation(s)
- Ralf Paus
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA; CUTANEON - Skin & Hair Innovations, Hamburg, Germany; Monasterium Laboratory, Münster, Germany.
| | - Alec Sevilla
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Internal Medicine, Lakeland Regional Health, Lakeland, Florida, USA
| | - James M Grichnik
- Department of Dermatology & Cutaneous Surgery, University of South Florida, Tampa, Florida, USA
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2
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van der Pol KH, Aljofan M, Blin O, Cornel JH, Rongen GA, Woestelandt AG, Spedding M. Drug Repurposing of Generic Drugs: Challenges and the Potential Role for Government. APPLIED HEALTH ECONOMICS AND HEALTH POLICY 2023; 21:831-840. [PMID: 37398987 PMCID: PMC10627937 DOI: 10.1007/s40258-023-00816-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/17/2023] [Indexed: 07/04/2023]
Abstract
Drug repurposing is the process of identifying a new use for an existing drug or active substance in an indication outside the scope of the original indication. Drug repurposing has important advantages including reduced development time and costs, and potentially large societal healthcare cost savings. However, current generic drug repurposing research faces a number of challenges in obtaining research funds. Furthermore, regardless of the success of a repurposing trial, commercial parties often lack interest in pursuing marketing authorisation for financial reasons, and academic researchers lack the knowledge, time and funding. Therefore, the new indication of a repurposed drug often does not make it 'on label'. We propose a large increase in public funding for generic drug repurposing research, including funds for the marketing authorisation process when a trial is successful, and a reduction in the regulatory burden of the marketing authorisation process for repurposed generic drugs.
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Affiliation(s)
- Karel H van der Pol
- Department of Internal Medicine, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mohamad Aljofan
- Department of Biomedical Science, Nazarbayev University School of Medicine, Nur-Sultan, Kazakhstan
- National Laboratory Astana, Nazarbayev University, Astana, 010000, Kazakhstan
| | - Olivier Blin
- Institut de Neurosciences des Systèmes, Aix Marseille Université, Inserm UMR 1106, Marseille, France
| | - Jan H Cornel
- Department of Cardiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Cardiology, Northwest Clinics, Alkmaar, The Netherlands
| | - Gerard A Rongen
- Department of Internal Medicine, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
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3
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Hussein RS, Atia T, Bin Dayel S. Impact of Thyroid Dysfunction on Hair Disorders. Cureus 2023; 15:e43266. [PMID: 37692605 PMCID: PMC10492440 DOI: 10.7759/cureus.43266] [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] [Accepted: 08/08/2023] [Indexed: 09/12/2023] Open
Abstract
Hair loss is a problem for everyone, regardless of their age or sex. The three most prevalent types of hair loss, telogen effluvium, alopecia areata, and androgenetic alopecia, have been associated with a variety of risk factors. Strong evidence links thyroid hormones (THs) to hair loss. THs control the growth, differentiation, metabolism, and thermogenesis of body cells. The skin is a significant target organ for THs; however, the cellular and molecular causes of thyroid dysfunction-related skin diseases remain unknown. Hyperthyroidism, hypothyroidism, and drug-induced hypothyroidism can induce widespread hair shedding. Little information is available regarding the incidence and effects of thyroid dysfunction on hair problems. This study aimed to review the impact and prevalence of thyroid disorders on hair loss. The conclusions drawn from this study highlight the underestimated prevalence and impact of thyroid disorders on hair loss. The review of scientific articles, including original research, review articles, and a case report, provides a comprehensive understanding of the topic. This research adds to the existing literature by enhancing our understanding of the relationship between thyroid dysfunction and hair disorders. It contributes to the body of evidence by reviewing relevant studies and summarizing the impact of thyroid disorders on hair loss. The study also highlights the gaps in knowledge and the need for more research in this area to improve the diagnosis and management of hair disorders associated with thyroid dysfunction.
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Affiliation(s)
- Ramadan S Hussein
- Department of Internal Medicine, Dermatology Unit, College of Medicine, Prince Sattam bin Abdulaziz University, Al-Kharj, SAU
| | - Tarek Atia
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University, Al-Kharj, SAU
| | - Salman Bin Dayel
- Department of Internal Medicine, Dermatology Unit, College of Medicine, Prince Sattam bin Abdulaziz University, Al-Kharj, SAU
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Popa A, Carsote M, Cretoiu D, Dumitrascu MC, Nistor CE, Sandru F. Study of the Thyroid Profile of Patients with Alopecia. J Clin Med 2023; 12:jcm12031115. [PMID: 36769763 PMCID: PMC9918246 DOI: 10.3390/jcm12031115] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Thyroid hormones are required for the physiological growth and maintenance of hair follicles. We aim to study the thyroid profile of patients with alopecia. This is a narrative review. PubMed literature was searched from 2013 to 2022. We followed different types of alopecia: alopecia areata (AA), androgenic alopecia in males and females, telogen effluvium (TE), frontal fibrosing alopecia (FFA), lichen planopilaris, and alopecia neoplastica (AN). AA shares a common autoimmune background with autoimmune thyroid diseases, either sporadic or belonging to autoimmune polyglandular syndromes. Some data suggested that AA is more severe if thyroid anomalies are confirmed, including subclinical dysfunction or positive antithyroid antibodies with normal hormone values. However, routine thyroid screening for patients with AA, if the patients are asymptomatic from a thyroid point of view and they have negative personal and family history of autoimmunity, remains controversial. TE, apart from the autoimmune type, associates thyroid anomalies of a hormonal assay (between 5.7% and 17%). FFA, mostly a postmenopausal entity (however, not exclusive), associates a higher prevalence of thyroid conditions (up to 50%) than the general population. However, these might have an age-dependent pattern, thus the association may be incidental since there are a limited number of studies. Overall, alopecia remains a very challenging condition for patients and physicians; a multidisciplinary team is required to improve the outcome and quality of life. The common autoimmune background is suggestive of some types of alopecia and thyroid disorders, yet, the underlying mechanisms are still a matter of debate. AA, TE, FFA, LPP, and, potentially, female pattern hair loss have been found to be connected with thyroid entities, thus a state of awareness from a dual perspective, of trichology and endocrinology, is helpful.
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Affiliation(s)
- Adelina Popa
- Department of Dermatovenerology, “Carol Davila University” of Medicine and Pharmacy & “Elias” University Emergency Hospital, 011461 Bucharest, Romania
| | - Mara Carsote
- Department of Endocrinology, “Carol Davila” University of Medicine and Pharmacy & “C.I. Parhon” National Institute of Endocrinology, 011461 Bucharest, Romania
- Correspondence:
| | - Dragos Cretoiu
- Department of Cellular and Molecular Biology, and Histology, Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy & National Institute for Mother and Child Health Alessandrescu-Rusescu, 011461 Bucharest, Romania
| | - Mihai Cristian Dumitrascu
- Department of Obstetrics and Gynaecology, “Carol Davila” University of Medicine and Pharmacy & University Emergency Hospital, 011461 Bucharest, Romania
| | - Claudiu-Eduard Nistor
- Department 4–Cardio-Thoracic Pathology, Thoracic Surgery II Discipline, “Carol Davila” University of Medicine and Pharmacy & Thoracic Surgery Department, “Carol Davila” Central Emergency University Military Hospital, 011461 Bucharest, Romania
| | - Florica Sandru
- Department of Dermatovenerology, “Carol Davila University” of Medicine and Pharmacy & “Elias” University Emergency Hospital, 011461 Bucharest, Romania
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Liu LP, Li MH, Zheng YW. Hair Follicles as a Critical Model for Monitoring the Circadian Clock. Int J Mol Sci 2023; 24:ijms24032407. [PMID: 36768730 PMCID: PMC9916850 DOI: 10.3390/ijms24032407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/30/2022] [Accepted: 01/20/2023] [Indexed: 01/27/2023] Open
Abstract
Clock (circadian) genes are heterogeneously expressed in hair follicles (HFs). The genes can be modulated by both the central circadian system and some extrinsic factors, such as light and thyroid hormones. These circadian genes participate in the regulation of several physiological processes of HFs, including hair growth and pigmentation. On the other hand, because peripheral circadian genes are synchronized with the central clock, HFs could provide a noninvasive and practical method for monitoring and evaluating multiple circadian-rhythm-related conditions and disorders among humans, including day and night shifts, sleep-wake disorders, physical activities, energy metabolism, and aging. However, due to the complexity of circadian biology, understanding how intrinsic oscillation operates using peripheral tissues only may be insufficient. Combining HF sampling with multidimensional assays such as detection of body temperature, blood samples, or certain validated questionnaires may be helpful in improving HF applications. Thus, HFs can serve as a critical model for monitoring the circadian clock and can help provide an understanding of the potential mechanisms of circadian-rhythm-related conditions; furthermore, chronotherapy could support personalized treatment scheduling based on the gene expression profile expressed in HFs.
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Affiliation(s)
- Li-Ping Liu
- Department of Dermatology, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China
- Institute of Regenerative Medicine, Jiangsu University, Zhenjiang 212001, China
- Correspondence: (L.-P.L.); (Y.-W.Z.)
| | - Meng-Huan Li
- Department of Dermatology, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China
- Institute of Regenerative Medicine, Jiangsu University, Zhenjiang 212001, China
| | - Yun-Wen Zheng
- Institute of Regenerative Medicine, Jiangsu University, Zhenjiang 212001, China
- Guangdong Provincial Key Laboratory of Large Animal Models for Biomedicine, South China Institute of Large Animal Models for Biomedicine, School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China
- Department of Medicinal and Life Sciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda 278-8510, Japan
- Department of Regenerative Medicine, Yokohama City University School of Medicine, Yokohama 234-0006, Japan
- Division of Regenerative Medicine, Center for Stem Cell Biology and Regenerative Medicine, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
- Correspondence: (L.-P.L.); (Y.-W.Z.)
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Bai Q, Tan J, Chai J, Shen L, Li N, Wu C. Preparation of Levothyroxine Transdermal Gels and Preliminary
Pharmacokinetic Study in Hypothyroidism Rat Model. LETT DRUG DES DISCOV 2022. [DOI: 10.2174/1570180819666220322151350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Hypothyroidism is a common disorder due to inadequate thyroid hormone secretion.
In patients with hypothyroidism, levothyroxine (LT4) is the treatment of choice, and tablets are the
most common dosage form. However, the main limitation of tablet LT4 is malabsorption.
Objective:
This study intends to develop a new dosage form of percutaneous drug delivery for levothyroxine.
Absorption of levothyroxine sodium through the application of gel formulation was studied using
a hypothyroidism rat model.
Methods:
A formulation of levothyroxine sodium gel was developed and selected. In-vitro transdermal
experiments were performed using the vertical Franz diffusion pool method, and gel formulation was
used for animal research (hypothyroidism rats model). Total 30 rats were randomly divided into 6 groups,
and one was the normal control group. The other 5 groups were prepared as hypothyroidism models. After
applying different doses of gel preparation to the rat model, we measured serum total thyroxine (TT4),
free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) using fluorescence
determination of luminescence immunoassay.
Results:
The optimum formulation of levothyroxine gels comprised 20% polyvinyl alcohol (PVA), 5%
glycerol, 2% azone, and 6% oleic acid. The application of levothyroxine sodium gel resulted in quick and
smooth action so that the predicted level of the normal control group could be reached within 2 weeks,
and it lasted steadily for 8 weeks.
Conclusion:
This research study successfully developed and tested an optimal formulation of levothyroxine
gel with therapeutic benefit on hypothyroidism in rats.
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Affiliation(s)
- Qingshuang Bai
- Department of Nuclear Medicine, Tianjin Fourth Central Hospital, The Fourth Central Clinical College, Tianjin Medical
University, Tianjin, China
| | - Jian Tan
- Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin,
China
| | - Jinyan Chai
- Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin,
China
| | - Linna Shen
- Department of Oncology and Haematology, Tianjin Fourth Central Hospital, The Fourth Central Clinical
College, Tianjin Medical University, Tianjin, China
| | - Ning Li
- Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin,
China
| | - Cailan Wu
- Department of Nuclear Medicine, Tianjin Fourth Central Hospital, The Fourth Central Clinical College, Tianjin Medical
University, Tianjin, China
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Paus R. Shining a (blue) light on hair follicle chronobiology and photobiomodulation. Exp Dermatol 2021; 30:189-192. [PMID: 33433942 DOI: 10.1111/exd.14271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Ralf Paus
- Dr Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA.,Centre for Dermatology Research, University of Manchester, NIHR Manchester Biomedical Research Centre, Manchester, UK.,Monasterium Laboratory, Münster, Germany
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Böhm M, Paus R. Towards a renaissance of dermatoendocrinology: Selected current frontiers. Exp Dermatol 2020; 29:786-789. [PMID: 33319935 DOI: 10.1111/exd.14177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Markus Böhm
- Department of Dermatology, University of Münster, Münster, Germany
| | - Ralf Paus
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA.,Centre for Dermatology Research, University of Manchester and NIHR Biomedical Research Centre, Manchester, UK.,Monasterium Laboratory, Münster, Germany
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