Acanthosis Nigricans: An Updated Review

Biomedical applications of tyrosinases and tyrosinase inhibitors

Tyrosinase is involved in several human diseases, among which hypopigmentation and depigmentation conditions (vitiligo, idiopathic guttate hypomelanosis, pityriasis versicolor, pityriasis alba) and hyperpigmentations (melasma, lentigines, post-inflammatory and periorbital hyperpigmentation, cervical idiopathic poikiloderma and acanthosis nigricans). There are increasing evidences that tyrosinase plays a relevant role in the formation and progression of melanoma, a difficult to treat skin tumor. Hydroquinone, azelaic acid and tretinoin (all-trans-retinoic acid) are clinically used in the management of some hyperpigmentations, whereas many novel chemotypes acting as tyrosinase inhibitors with potential antimelanoma action are being investigated. Kojic acid, hydroquinone, its glycosylated derivative arbutin, or the resorcinol derivative rucinol are used in cosmesis in creams as skin whitening agents, whereas no antimelanoma tyrosinase inhibitor reached clinical trials so far, although thiamidol is a recently approved new tyrosinase inhibitor for the treatment of melasma. Kojic acid and vitamin C are used for avoiding vegetable/food oxidative browning due to the tyrosinase-catalyzed reactions, whereas bacterial enzymes show potential in biotechnological applications, for the production of mixed melanins, for protein cross-linking reactions, for producing phenol(s) biosensors, of for the production of L-DOPA, an anti-Parkinson's disease drug.

Global hotspots and trends in Acanthosis nigricans research: A bibliometric and visualized analysis

BACKGROUND

Acanthosis nigricans (AN) is a common skin disease characterized by clear pigmented patches on the folds of the skin. However, the AN research field lacks scientific and comprehensive bibliometric analysis. This article aims to use bibliometric methods to summarize and visualize the distribution patterns, research hotspots, and development trends of AN literature.

METHODS

Literature from 1900 to 2024 was retrieved from the Web of Science Core Collection database through AN's thematic search. Using CiteSpace, VOSviewer, and Excel 2019, conduct a comprehensive analysis of the number of publications, countries/regions, institutions, authors, journals, highly cited literature, keywords, and so on, and sort out the hotspots and directions of AN.

RESULTS

From 1900 to 2024, 1675 publications were included in the bibliometric analysis, showing a steady annual increase in the number of publications. The United States leads in this research field, with the University of Texas System being a key research institution. The Journal of Clinical Endocrinology & Metabolism has the highest number of published papers. The most cited article is "Syndromes of Insulin Resistance and Acanthosis Nigricans: Insulin-Receptor Disorders in Man" (1976). The author Taylor, SI, has published the most papers. "Acanthosis nigricans" is the most frequently occurring keyword. The main research hotspots and frontier areas in AN research are as follows: (1) The relationship between AN and other diseases is a popular research topic; (2) The connection between AN and insulin resistance (IR) is a current research focus; (3) Treatment of AN, with an emphasis on addressing the underlying causes and improving local skin conditions, represents the cutting edge of this field.

CONCLUSION

This study summarizes the research trends and hotspots in the field of AN, offering valuable information and insights for scholars focused on AN scientific research, and providing a reference for future research directions.

Cellular immune response to a single dose of live attenuated hepatitis a virus vaccine in obese children and adolescents

Background

Limited data are currently available regarding the cellular immune response to a live attenuated hepatitis A virus (HAV) vaccine, especially in children with obesity. The objective of this retrospective cohort study was to compare the activation of antigen-specific interferon (IFN)-γ+ T cells in obese children and adolescents with healthy individuals before and after immunization with a single dose of live attenuated HAV vaccine.

Methods

Blood samples were obtained from the 2021 study by Dumrisilp et al. investigating the immunogenicity of the live attenuated hepatitis A vaccine in children and young adults. Prior to enrollment, all 212 subjects had never received any HAV vaccine and tested negative for anti-HAV antibodies. The participants were vaccinated with a freeze-dried, live attenuated HAV vaccine of the H2 strain. In this study, we analyzed the stored peripheral blood mononuclear cells (PBMCs) obtained from a subgroup of 30 obese subjects and 30 normal-weight healthy controls of the same age and sex. PBMCs were collected before and 8-9 weeks after HAV vaccination for further analysis. These cells were stimulated with a recombinant antigen derived from HAV-VP3, and the immune response was evaluated using the IFN-γ enzyme-linked immunospot (ELISpot) assay.

Results

The between-group analysis indicated that the T-cell response of obese participants was comparable to that of normal-weight controls both before and after vaccination. The change in IFN-γ production from before to after vaccination in the obese group was not significantly different from that of the control group. Additionally, in the obese group, no correlation was found between IFN-γ production and clinical characteristics such as sex, body mass index, waist circumference, and acanthosis nigricans.

Conclusion

Testing for cellular immune response provides a comprehensive understanding of the overall immune response to vaccination. This study, the first to explore this significant aspect, suggests that obesity does not affect the short-term cellular immune response to live attenuated HAV vaccination.

Obesity Influences T CD4 Lymphocytes Subsets Profiles in Children and Adolescent's Immune Response

BACKGROUND

OBJECTIVES: Evidence shows that CD4+ T cells are altered in obesity and play a significant role in the systemic inflammation in adults with the disease. Because the profile of these cells is poorly understood in the pediatric population, this study aims to investigate the profile of CD4+ T lymphocytes and the plasma levels of cytokines in this population.

METHODS

Using flow cytometry, we compared the expression profile of lymphocyte markers, master transcription factors, cytokines, and molecules involved in the regulation of the immune response in CD4+ T cells from children and adolescents with obesity (OB group, n = 20) with those with eutrophy group (EU group, n = 16). Plasma levels of cytokines in both groups were determined by CBA.

RESULTS

The OB group presents a lower frequency of CD3+ T cells, as well as a decreased frequency of CD4+ T cells expressing CD28, IL-4, and FOXP3, but an increased frequency of CD4+IL-17A+ cells compared with the EU group. The frequency of CD28 is increased in Th2 and Treg cells in the OB group, whereas CTLA-4 is decreased in all subpopulations compared with the EU group. Furthermore, Th2, Th17, and Treg profiles can differentiate the EU and OB groups. IL-10 plasma levels are reduced in the OB group and negatively correlated with adiposity and inflammatory parameters.

CONCLUSIONS

CD4+ T cells have an altered pattern of expression in children and adolescents with obesity, contributing to the inflammatory state and clinical characteristics of these patients.

Acanthosis nigricans - a potentially useful clue to the presence of significant occult disease at autopsy

A 19-year-old male was found dead in his apartment. At autopsy he was morbidly obese (Body mass index; BMI - 40.5) with multiple areas of velvety pigmented thickening of the skin in folds around the neck, in the axillae, in the inframammary regions, over the anterior waistline and groin regions and over the dorsal aspects of the feet. These had the typical appearance of acanthosis nigricans. Internal examination revealed aspiration of gastric contents into the airways. Vitreous humour biochemistry showed markedly elevated levels of both glucose (62.9 mmol/L) and β-hydroxybutyrate (13.54 mmol/L). Death was, therefore, due to aspiration pneumonia complicating diabetic ketoacidosis on a background of morbid obesity. The initial indicator of underlying diabetes, in conjunction with obesity had been acanthosis nigricans.

Efficacy and safety of lasers versus topical medications for acanthosis nigricans and pseudo-acanthosis nigricans treatment: a systematic review

Acanthosis nigricans (AN) is a cutaneous disorder identified by well-defined pigmented plaques mostly detected on skin folds. Timely diagnosis and treatment of AN is essential as it could be an early manifestation of an underlying condition. The treatment of choice for AN has not been determined yet. Our study aimed to compare the efficacy and safety of various lasers with topical medications, including cream and peel. PubMed, Scopus, and Web of Science databases, as well as the Google Scholar search engine, were thoroughly searched until May 1st, 2023. Study selection was restricted to clinical trials published in English language comparing lasers with topical treatments. This study followed the PRISMA guidelines for systematic reviews and meta-analyses. Out of 1748 studies, Six clinical trials met our inclusion criteria, with 133 patients. We examined laser therapies, including fractional CO2 laser, 1550-nm erbium fiber laser, and long-pulsed alexandrite laser, while the topical treatments comprised glycolic acid (GA) peel, retinoic acid peel, trichloroacetic acid (TCA) peel, and tretinoin cream. In two studies, GA peel demonstrated favorable results compared to fractional CO2 laser. Besides, fractional CO2 laser exhibited efficacy, surpassing TCA peel in AN management. Additionally, a fractional 1550-nm erbium fiber laser displayed superiority over tretinoin cream in reducing average roughness. Similarly, a long-pulsed alexandrite laser demonstrated its effectiveness in axillary AN treatment compared to the combination of tretinoin and ammonium lactate. Overall, the findings revealed that laser therapy was associated with superior results. Moreover, topical treatments are safe and efficacious in AN management.

Clinical factors associated with remission of obese acanthosis nigricans after laparoscopic sleeve gastrectomy: a prospective cohort study

BACKGROUND

Acanthosis nigricans (AN) involves skin hyperpigmentation in body folds and creases. Obesity-associated AN (OB_AN) is the most common type of AN. The skin condition of obese patients with AN can be improved through bariatric surgery, such as laparoscopic sleeve gastrectomy (LSG), after weight loss. However, the contributing factors to the remission of AN after surgery are still not fully determined. The authors aimed to assess the metabolic and pathological factors associated with remission of AN following LSG in obese individuals.

METHODS

The study included 319 obese patients who underwent LSG at our hospital. The subjects were divided into obesity (OB) only (OB, n =178) or OB with AN (OB_AN, n =141) groups. The basic clinical and metabolic indices and the dermatological features via reflectance confocal microscopy and histology were collected from patients prior to and after LSG.

RESULTS

OB_AN patients had higher fasting plasma glucose, homeostatic model assessment for insulin resistance, and testosterone levels than OB patients. LSG could significantly improve the biochemical and histopathological features of OB_AN patients. The remissive rate of OB_AN patients was about 86.5% (122 out of 141) after surgery. The remission of OB_AN skin lesions was positively correlated with testosterone levels ( P <0.01). In addition, there was a significant positive correlation between changes in AN scores and epidermal thickness and skin pigmentation scores after surgery ( P <0.01).

CONCLUSION

The remissive rate of OB_AN after LSG is associated with improved testosterone levels and reduced epidermal thickness and skin pigmentation levels.