The Role of the Renin-Angiotensin System and Vitamin D in Keloid Disorder-A Review

Pharmacotherapy for Keloids and Hypertrophic Scars

Keloids (KD) and hypertrophic scars (HTS), which are quite raised and pigmented and have increased vascularization and cellularity, are formed due to the impaired healing process of cutaneous injuries in some individuals having family history and genetic factors. These scars decrease the quality of life (QOL) of patients greatly, due to the pain, itching, contracture, cosmetic problems, and so on, depending on the location of the scars. Treatment/prevention that will satisfy patients' QOL is still under development. In this article, we review pharmacotherapy for treating KD and HTS, including the prevention of postsurgical recurrence (especially KD). Pharmacotherapy involves monotherapy using a single drug and combination pharmacotherapy using multiple drugs, where drugs are administered orally, topically and/or through intralesional injection. In addition, pharmacotherapy for KD/HTS is sometimes combined with surgical excision and/or with physical therapy such as cryotherapy, laser therapy, radiotherapy including brachytherapy, and silicone gel/sheeting. The results regarding the clinical effectiveness of each mono-pharmacotherapy for KD/HTS are not always consistent but rather scattered among researchers. Multimodal combination pharmacotherapy that targets multiple sites simultaneously is more effective than mono-pharmacotherapy. The literature was searched using PubMed, Google Scholar, and Online search engines.

The mechanism of oxidative stress in keloid fibroblasts and the experimental study of early application of angiotensin-converting enzyme inhibitor

Objective To investigate the protective effects of an angiotensin-converting enzyme inhibitor after inducing oxidative stress on keloid fibroblasts. Methods Primary keloid fibroblasts were isolated and cultured by enzyme digestion combined with the tissue adhesion method in vitro, and the third to fifth generations of cells were selected for the experiment. For 24 hours, keloid fibroblasts were treated with different concentrations of hydrogen peroxide. Different concentrations of angiotensin-converting enzyme inhibitor were added to the keloid fibroblast culture medium, and then the cells were treated with hydrogen peroxide for 24 hours. Results With the increase of hydrogen peroxide concentration, the growth of keloid fibroblasts was inhibited and the levels of malondialdehyde, superoxide dismutase, and reactive oxygen species increased gradually, accompanied by an increase in the expression of nicotinamide adenine dinucleotide phosphate oxidase and collagen I mRNA. The expression of nicotinamide adenine dinucleotide phosphate oxidase-mRNA in keloid fibroblasts and the formation of reactive oxygen species in keloid fibroblasts were induced by different concentrations of angiotensin II, and the most significant effect was at 10-5 mmol/mL. The effects of diphenyleneiodonium chloride (NOX inhibitor), N-acetylcysteine (reactive oxygen species inhibitor) and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) RNA treatment on angiotensin II-induced nicotinamide adenine dinucleotide phosphate oxidase and collagen I increased significantly. Hydrogen peroxide and angiotensin II alone or combined can induce NADPH oxidase and reactive oxygen species expression in keloid fibroblasts. When the angiotensin-converting enzyme inhibitor was added, the expression of NADPH oxidase and reactive oxygen species in keloid induced by hydrogen peroxide and angiotensin II could be inhibited. Conclusion Oxidative stress can lead to increased expression of reactive oxygen species, NADPH oxidase and collagen I in keloid fibroblasts, suggesting oxidative stress mediates the migration of human keloid fibroblasts and extracellular matrix synthesis.

IL-4 and CCR7 play an important role in the development of keloids in patients with a family history

BACKGROUND

The occurrence of keloids tends to show family clusters and more severe symptoms in patients with a family history of the condition, but their pathological mechanisms remain unclear. In this study, we aimed to investigate the differences in genetic susceptibility between keloid patients with a family history of keloids and sporadic patients with sporadic keloids and explore potential therapeutic targets of keloids at the molecular level.

METHODS

High-throughput sequencing data were obtained from normal skin tissue of patients with a family history of keloids (FN group) and normal skin tissue from sporadic patients (N group). Bioinformatics analysis was employed to identify hub genes. Promising hub genes were identified using RT-qPCR, immunohistochemistry and immunofluorescence assays, and Western blotting. GO and KEGG pathway enrichment analysis was performed to determine the main functions between the two groups.

RESULTS

Patients with a family history of keloids had more severe clinical symptoms (Ρ = -0.749, P < 0.001). The expression of IL-4 and CCR7 was significantly different between patients with a family history of keloids and those with sporadic keloids. The high expression of IL-4 and the low expression of CCR7 in the FN group may be of key importance in explaining why keloids run in families (P < 0.05).

CONCLUSION

Having a family history of keloids is a risk factor for increased severity of keloids. IL-4 and CCR7 play an important role in the development of keloids in patients with a family history of the condition and may represent new targets for the treatment of keloids.

Insights Into Vascular Anomalies, Cancer, and Fibroproliferative Conditions: The Role of Stem Cells and the Renin-Angiotensin System

Cells exhibiting embryonic stem cell (ESC) characteristics have been demonstrated in vascular anomalies (VAs), cancer, and fibroproliferative conditions, which are commonly managed by plastic surgeons and remain largely unsolved. The efficacy of the mTOR inhibitor sirolimus, and targeted therapies that block the Ras/BRAF/MEK/ERK1/2 and PI3KCA/AKT/mTOR pathways in many types of cancer and VAs, further supports the critical role of ESC-like cells in the pathogenesis of these conditions. ESC-like cells in VAs, cancer, and fibroproliferative conditions express components of the renin-angiotensin system (RAS) – a homeostatic endocrine signaling cascade that regulates cells with ESC characteristics. ESC-like cells are influenced by the Ras/BRAF/MEK/ERK1/2 and PI3KCA/AKT/mTOR pathways, which directly regulate cellular proliferation and stemness, and interact with the RAS at multiple points. Gain-of-function mutations affecting these pathways have been identified in many types of cancer and VAs, that have been treated with targeted therapies with some success. In cancer, the RAS promotes tumor progression, treatment resistance, recurrence, and metastasis. The RAS modulates cellular invasion, migration, proliferation, and angiogenesis. It also indirectly regulates ESC-like cells via its direct influence on the tissue microenvironment and by its interaction with the immune system. In vitro studies show that RAS inhibition suppresses the hallmarks of cancer in different experimental models. Numerous epidemiological studies show a reduced incidence of cancer and improved survival outcomes in patients taking RAS inhibitors, although some studies have shown no such effect. The discovery of ESC-like cells that express RAS components in infantile hemangioma (IH) underscores the paradigm shift in the understanding of its programmed biologic behavior and accelerated involution induced by β-blockers and angiotensin-converting enzyme inhibitors. The findings of SOX18 inhibition by R-propranolol suggests the possibility of targeting ESC-like cells in IH without β-adrenergic blockade, and its associated side effects. This article provides an overview of the current knowledge of ESC-like cells and the RAS in VAs, cancer, and fibroproliferative conditions. It also highlights new lines of research and potential novel therapeutic approaches for these unsolved problems in plastic surgery, by targeting the ESC-like cells through manipulation of the RAS, its bypass loops and converging signaling pathways using existing low-cost, commonly available, and safe oral medications.

The Role of the Renin-Angiotensin System in the Cancer Stem Cell Niche

Cancer stem cells (CSCs) drive metastasis, treatment resistance, and tumor recurrence. CSCs reside within a niche, an anatomically distinct site within the tumor microenvironment (TME) that consists of malignant and non-malignant cells, including immune cells. The renin-angiotensin system (RAS), a critical regulator of stem cells and key developmental processes, plays a vital role in the TME. Non-malignant cells within the CSC niche and stem cell signaling pathways such as the Wnt, Hedgehog, and Notch pathways influence CSCs. Components of the RAS and cathepsins B and D that constitute bypass loops of the RAS are expressed on CSCs in many cancer types. There is extensive in vitro and in vivo evidence showing that RAS inhibition reduces tumor growth, cell proliferation, invasion, and metastasis. However, there is inconsistent epidemiological data on the effect of RAS inhibitors on cancer incidence and survival outcomes, attributed to different patient characteristics and methodologies used between studies. Further mechanistic studies are warranted to investigate the precise effects of the RAS on CSCs directly and/or the CSC niche. Targeting the RAS, its bypass loops, and convergent signaling pathways participating in the TME and other key stem cell pathways that regulate CSCs may be a novel approach to cancer treatment.

Keloid fibroblasts have elevated and dysfunctional mechanotransduction signaling that is independent of TGF-β

BACKGROUND

Fibroblasts found in keloid tissues are known to present an altered sensitivity to microenvironmental stimuli. However, the impact of changes in extracellular matrix stiffness on phenotypes of normal fibroblasts (NFs) and keloid fibroblasts (KFs) is poorly understood.

OBJECTIVES

Investigation the impact of matrix stiffness on NFs and KFs mainly via detecting yes-associated protein (YAP) expression.

METHODS

We used fibronectin-coated polyacrylamide hydrogel substrates with a range from physiological to pathological stiffness values with or without TGF-β (fibrogenic inducer). Atomic force microscopy was used to measure the stiffness of fibroblasts. Cellular mechanoresponses were screened by immunocytochemistry, Western blot and Luminex assay.

RESULTS

KFs are stiffer than NFs with greater expression of α-SMA. In NFs, YAP nuclear translocation was induced by increasing matrix stiffness as well as by stimulation with TGF-β. In contrast, KFs showed higher baseline levels of nuclear YAP that was not responsive to matrix stiffness or TGF-β. TGF-β1 induced p-SMAD3 in both KFs and NFs, demonstrating the pathway was functional and not hyperactivated in KFs. Moreover, blebbistatin suppressed α-SMA expression and cellular stiffness in KFs, linking the elevated YAP signaling to keloid phenotype.

CONCLUSIONS

These data suggest that whilst normal skin fibroblasts respond to matrix stiffness in vitro, keloid fibroblasts have elevated activation of mechanotransduction signaling insensitive to the microenvironment. This elevated signaling appears linked to the expression of α-SMA, suggesting a direct link to disease pathogenesis. These findings suggest changes to keloid fibroblast phenotype related to mechanotransduction contribute to disease and may be a useful therapeutic target.

Therapeutic Strategies by Regulating Interleukin Family to Suppress Inflammation in Hypertrophic Scar and Keloid

Hypertrophic scar (HS) and keloid are fibroproliferative disorders (FPDs) of the skin due to aberrant wound healing, which cause disfigured appearance, discomfort, dysfunction, psychological stress, and patient frustration. The unclear pathogenesis behind HS and keloid is partially responsible for the clinical treatment stagnancy. However, there are now increasing evidences suggesting that inflammation is the initiator of HS and keloid formation. Interleukins are known to participate in inflammatory and immune responses, and play a critical role in wound healing and scar formation. In this review, we summarize the function of related interleukins, and focus on their potentials as the therapeutic target for the treatment of HS and keloid.

β-blocker therapy for infantile hemangioma

INTRODUCTION

Fifteen percent of proliferating infantile hemangioma (IH) require intervention because of the threat to function or life, ulceration, or tissue distortion. Propranolol is the mainstay treatment for problematic proliferating IH. Other β-blockers and angiotensin-converting enzyme (ACE) inhibitors have been explored as alternative treatments.

AREAS COVERED

The demonstration of a hemogenic endothelium origin of IH, with a neural crest phenotype and multi-lineage differentiation capacity, regulated by the renin-angiotensin system, underscores its programmed biologic behavior and accelerated involution induced by propranolol, other β-blockers and ACE inhibitors. We review the indications, dosing regimens, duration of treatment, efficacy and adverse effects of propranolol, and therapeutic alternatives including oral atenolol, acebutolol, nadolol, intralesional propranolol injections, topical propranolol and timolol, and oral captopril.

EXPERT OPINION

Improved understanding of the biology of IH provides insights into the mechanism of action underscoring its accelerated involution induced by propranolol, other β-blockers and ACE inhibitors. More research is required to understand the optimal dosing and duration, efficacy and safety of these alternative therapies. Recent demonstration of propranolol's actions mediated by non-β-adrenergic isomer R-propranolol on stem cells, offers an immense opportunity to harness the efficacy of β-blockers to induce accelerated involution of IH, while mitigating their β-adrenergic receptor-mediated adverse effects.

Acne keloidalis nuchae and hypertension in black subjects: a case–control study

Objective

The aim of this case–control study was to look for an association between hypertension and acne keloidalis nuchae (AKN) in black subjects.

Results

We recruited 303 consenting subjects comprising 101 patients with AKN and 202 controls, case-matched by age (± 5 years). The mean patients age was 34.9 ± 10.7 years versus 35.6 ± 11.2 years for controls. The average duration of AKN progression in cases prior to consultation was 1831 days (5 years). The most frequently observed AKN lesions were papules (73/101; 72.3%), fibrous scars (42/101; 41.6%) and folliculitis/pustules (41/101; 40.6%). In terms of quality of life, the mean score of dermatology life quality index was 8.3 ± 5.2 (extremes: 0 to 22). In multivariate analysis, having a BMI of 25 kg/m² or more (OR = 4.91; p < 0.001) and having systolic hypertension (OR = 1.22; p = 0.010) were associated with AKN.

Vitamin D can be effective on the prevention of COVID-19 complications: A narrative review on molecular aspects

The widespread COVID-19 pandemic has been, currently, converted to a catastrophic human health challenge. Vitamin D (VD) and its metabolites have been used as a palliative treatment for chronic inflammatory and infectious diseases from ancient times. In the current study, some molecular aspects of the potential effects of VD against COVID-19 side-effects have been discussed. An arguable role in autophagy or apoptosis control has been suggested for VD through calcium signaling at the mitochondrial and ER levels. 1,25(OH)2D3 is also an immunomodulator that affects the development of B-cells, T-cells, and NK cells in both innate and acquired immunity. The production of some anti-microbial molecules such as defensins and cathelicidins is also stimulated by VD. The overexpression of glutathione, glutathione peroxidase, and superoxide dismutase, and down-regulation of NADPH oxidase are induced by VD to reduce the oxidative stress. Moreover, the multi-organ failure due to a cytokine storm induced by SARS-CoV2 in COVID-19 may be prevented by the immunomodulatory effects of VD. It can also downregulate the renin-angiotensin system which has a protective role against cardiovascular complications induced by COVID-19. Given the many experimental and molecular evidences due to the potential protective effects of VD on the prevention of the COVID-19-induced morbidities, a VD supplementation is suggested to prevent the lethal side-effects of the infection. It is particularly recommended in VD-deficient patients or those at greater risk of serious or critical effects of COVID-19, including the elderly, and patients with pre-existing chronic diseases, especially those in nursing homes, care facilities, and hospitals.