Regulation of cytokines by small RNAs during skin inflammation

The m-TORC1 inhibitor Sirolimus increases the effectiveness of Photodynamic therapy in the treatment of cutaneous Squamous Cell Carcinoma, impairing NRF2 antioxidant signaling

Squamous Cell Carcinoma (SCC) is a subtype of Non-Melanoma Skin Cancer, the most common group of malignancies worldwide. Photodynamic therapy (PDT) is a non-invasive treatment approved for specific subtypes of SCC. Some malignancies resist PDT, forming more aggressive tumors and multiple relapses. Thus, new approaches aimed at optimizing the response to PDT are needed. The mTORC1 inhibitor rapamycin, also known as Sirolimus (SRL), interferes with protein synthesis and cell metabolism. The use of SRL as an immunosuppressant is associated to lower rates of SCC in kidney-transplanted patients, which are frequently affected by this pathology. We have evaluated SRL pre-treatment efficacy to enhance the damage induced by PDT with Methyl 5-aminolevulinate in two different cutaneous SCC established cell lines (SCC13 and A431) in vitro and therapy sensitization in PDT-resistant cell lines. We tested for the first time the SRL + PDT combination in a SKH-1 mouse model of photocarcinogenesis, diminishing the frequency of lesions and restraining tumor growth. Molecular studies revealed that protoporphyrin IX and reactive oxygen species production induced by PDT were promoted by SRL pre-treatment. Lastly, SRL modifies the expression and intracellular location of NRF2, interfering with the downstream antioxidant response modulated by NQO1 and HO-1. In conclusion, we propose SRL as a potential adjuvant to enhance PDT efficacy for SCC treatment.

Revisiting p38 Mitogen-Activated Protein Kinases (MAPK) in Inflammatory Arthritis: A Narrative of the Emergence of MAPK-Activated Protein Kinase Inhibitors (MK2i)

The p38 mitogen-activated protein kinase (p38-MAPK) is a crucial signaling pathway closely involved in several physiological and cellular functions, including cell cycle, apoptosis, gene expression, and responses to stress stimuli. It also plays a central role in inflammation and immunity. Owing to disparate p38-MAPK functions, it has thus far formed an elusive drug target with failed clinical trials in inflammatory diseases due to challenges including hepatotoxicity, cardiac toxicity, lack of efficacy, and tachyphylaxis, which is a brief initial improvement with rapid disease rebound. To overcome these limitations, downstream antagonism of the p38 pathway with a MAPK-activated protein kinase (MAPKAPK, also known as MK2) blockade has demonstrated the potential to abrogate inflammation without the prior recognized toxicities. Such MK2 inhibition (MK2i) is associated with robust suppression of key pro-inflammatory cytokines, including TNFα and IL-6 and others in experimental systems and in vitro. Considering this recent evidence regarding MK2i in inflammatory arthritis, we revisit the p38-MAPK pathway and discuss the literature encompassing the challenges of p38 inhibitors with a focus on this pathway. We then highlight how novel MK2i strategies, although encouraging in the pre-clinical arena, may either show evidence for efficacy or the lack of efficacy in emergent human trials data from different disease settings.

Orchestrated Cytokines Mediated by Biologics in Psoriasis and Its Mechanisms of Action

Psoriasis is an autoimmune disease mediated by disturbed T cells and other immune cells, and is defined by deep-red, well-demarcated skin lesions. Due to its varied etiologies and indefinite standard pathogenesis, it is challenging to consider the right treatment exclusively for each psoriasis patient; thus, researchers yearn to seek even more precise treatments other than topical treatment and systemic therapy. Using biologics to target specific immune components, such as upregulated cytokines secreted by activated immune cells, is the most advanced therapy for psoriasis to date. By inhibiting the appropriate pro-inflammatory cytokines, cellular signaling can be altered and, thus, can inhibit further downstream inflammatory pathways. Herein, the roles of cytokines with their mechanisms of action in progressing psoriasis and how the usage of biologics alleviates cellular inflammation are discussed. In addition, other potential pro-inflammatory cytokines, with their mechanism of action, are presented herein. The authors hope that this gathered information may benefit future research in expanding the discovery of targeted psoriasis therapy.

Ischemia/reperfusion injured intestinal epithelial cells cause cortical neuron death by releasing exosomal microRNAs associated with apoptosis, necroptosis, and pyroptosis

To date, there is no good evidence that intestine epithelial cells (IEC) affected by ischemia/reperfusion (I/R) injury are able to cause cortical neuron injury directly. Additionally, it remains unclear whether the neuronal damage caused by I/R injured IEC can be affected by therapeutic hypothermia (TH, 32 °C). To address these questions, we performed an oxygen–glucose deprivation (OGD) affected IEC-6-primary cortical neuron coculture system under normothermia (37 °C) or TH (32 °C) conditions. It was found that OGD caused hyperpermeability in IEC-6 cell monolayers. OGD-preconditioned IEC-6 cells caused cortical neuronal death (e.g., decreased cell viability), synaptotoxicity, and neuronal apoptosis (evidenced by increased caspase-3 expression and the number of TUNEL-positive cells), necroptosis (evidenced by increased receptor-interacting serine/threonine-protein kinase-1 [RIPK1], RIPK3 and mixed lineage kinase domain-like pseudokinase [MLKL] expression), and pyroptosis (evidenced by an increase in caspase-1, gasdermin D [GSDMD], IL-1β, IL-18, the apoptosis-associated speck-like protein containing a caspase recruitment domain [ASC], and nucleotide oligomerization domain [NOD]-like receptor [NLRP]-1 expression). TH did not affect the intestinal epithelial hyperpermeability but did attenuate OGD-induced neuronal death and synaptotoxicity. We also performed quantitative real-time PCR to quantify the genes encoding 84 exosomal microRNAs in the medium of the control-IEC-6, the control-neuron, the OGD-IEC-6 at 37 °C, the OGD-IEC-6 at 32 °C, the neuron cocultured with OGD-IEC-6 at 37 °C, and the neurons cocultured with OGD-IEC-6 at 32 °C. We found that the control IEC-6 cell s or cortical neurons are able to secrete a basal level of exosomal miRNAs in their medium. OGD significantly up-regulated the basal level of each parameter for IEC-6 cells. As compared to those of the OGD-IEC-6 cells or the control neurons, the OGD-IEC-6 cocultured neurons had significantly higher levels of 19 exosomal miRNAs related to apoptosis, necroptosis, and/or pyroptosis events. Our results identify that I/R injured intestinal epithelium cells can induce cortical neuron death via releasing paracrine mediators such as exosomal miRNAs associated with apoptosis, necroptosis, and/or pyroptosis, which can be counteracted by TH.

Kinetic Cytokine Secretion Profile of LPS-Induced Inflammation in the Human Skin Organ Culture

Several in vitro models that mimic different aspects of local skin inflammation exist. The use of ex vivo human skin organ culture (HSOC) has been reported previously. However, comprehensive evaluation of the cytokine secretory capacity of the system and its kinetics has not been performed. Objective: the aim of the current study was to investigate the levels and secretion pattern of key cytokine from human skin tissue upon lipopolysaccharide (LPS) stimulation. HSOC maintained in an air–liquid interface was used. Epidermal and tissue viability was monitored by MTT and Lactate Dehydrogenase (LDH) activity assay, respectively. Cytokine levels were examined by ELISA and multiplex array. HSOCs were treated without or with three different LPS subtypes and the impact on IL-6 and IL-8 secretion was evaluated. The compounds enhanced the secreted levels of both cytokines. However, differences were observed in their efficacy and potency. Next, a kinetic multiplex analysis was performed on LPS-stimulated explants taken from three different donors to evaluate the cytokine secretion pattern during 0–72 h post-induction. The results revealed that the pro-inflammatory cytokines IL-6, IL-8, TNFα and IL-1β were up-regulated by LPS stimuli. IL-10, an anti-inflammatory cytokine, was also induced by LPS, but exhibited a different secretion pattern, peak time and maximal stimulation values. IL-1α and IL-15 showed donor-specific changes. Lastly, dexamethasone attenuated cytokine secretion in five independent repetitions, supporting the ability of the system to be used for drug screening. The collective results demonstrate that several cytokines can be used as valid inflammatory markers, regardless of changes in the secretion levels due to donor’s specific alterations.

Study of differential expression of miRNAs in lung tissue of mice submitted to experimental infection by Paracoccidioides brasiliensis

MicroRNAs (miRNAs) are small single stranded RNA sequences involved in post-transcriptional regulation of different biological and physiological processes. Paracoccidioidomycosis (PCM) is an infection caused by Paracoccidioides brasiliensis, and it is a major cause of mortality due to systemic mycoses in Brazil. To date, there have been few reports on the role of miRNAs in the immune response against fungi, especially PCM. The objective of this study was to evaluate the differential expression of miRNAs related to the inflammatory response associated with pulmonary infection by P. brasiliensis. For this purpose, lungs from BALB/c mice, intravenously infected with P. brasiliensis (2.7×107 yeast cells/ml, n = 12) and noninfected BALB/c mice (n = 8), were collected at the 28 and 56 day after infection. The lung parenchyma presented a great number of yeast cells, granulomas, and edema at 28 days and a framework of resolution of the inflammatory process after 56 days. The mRNAs gata-3, ror-γt, foxp3, and IL-6 were positively regulated at the moment at the 56 day, while the TGF-β1 mRNA was positively regulated at both moments. The miRNAs 126a-5p, 340-5p, 30b-5p, 19b-3p, 221-3p, 20a-5p, 130a-3p, and 301a-3p, 466k presented the greatest increase in expression levels 28 days after infection, and the miRNAs let-7f-5p, let-7a-5p, 5p-26b, let-7e-5p and 369-3p, 466k presented a greater increase in levels of expression 56 days after infection. This study shows a set of differentially expressed miRNAs possibly involved in the immune response in mice during pulmonary infection by P. brasiliensis.

Tumor necrosis factor-α downregulates the REIC/Dkk-3 tumor suppressor gene in normal human skin keratinocytes

Our previous studies revealed that REIC/Dkk-3 was expressed various tissues, including skin keratinocytes. The aim of the present study was to identify the factors that regulate the expression of the dickkopf Wnt signaling pathway inhibitor 3 (REIC/Dkk‑3) tumor suppressor gene in normal human skin keratinocytes (NHKs). Several growth factors and cytokines that have previously been reported to be involved in the growth and differentiation of keratinocytes were screened as potential regulators. Western blot analysis was performed using protein from NHKs cultured with/without various factors including the epidermal growth factor, tumor necrosis factor‑α, transforming growth factor‑β, interleukin (IL)‑1F9, IL‑6, IL‑8 and Ca2+. The results indicated that only TNF‑α downregulated REIC/Dkk‑3 expression in NHKs. Subsequently, TNF‑α was confirmed to reduce the expression levels of REIC/Dkk‑3 in mouse skin tissue and hair culture models. TNF‑α‑mediated downregulation of REIC/Dkk‑3 expression in NHKs was abrogated by the addition of a TNF‑α‑specific antibody. In conclusion, the results indicate that TNF‑α downregulates REIC/Dkk‑3 expression in normal skin keratinocytes.

Increased MicroRNA-1266 levels as a biomarker for disease activity in psoriasis vulgaris

BACKGROUND

Increasing evidence has shown that serum microRNA (miR) levels are useful biomarkers for the diagnosis, prognosis, and therapeutic value in various diseases. Psoriasis is characterized by a specific miR expression profile, with a characteristic miR signature, distinct from that of healthy skin.

OBJECTIVES

To understand the role of miR-1266 in the pathogenesis of psoriasis and to explore if it has the potential as a blood biomarker. We assessed serum miR-1266 levels in patients with psoriasis before and after treatment and compared it with controls. In addition, we evaluated the relationship between miR-1266 and clinical severity in psoriasis before and after treatment.

METHODS

miR-1266 was measured using real-time polymerase chain reaction in 35 patients with chronic plaque psoriasis and 35 healthy controls before and after treatment. Moreover, the correlation between miR-1266 levels and psoriasis area and severity index score was determined.

RESULTS

Serum miR-1266 levels were considerably higher in patients with psoriasis than in healthy control subjects. Furthermore, miR-1266 levels showed a strong positive correlation with psoriasis area and severity index score before and after treatment, having a marked decline with therapy.

CONCLUSION

miR-1266 may have an important role in the pathogenesis of psoriasis vulgaris. This may presumably have possible future implications on the treatment of this chronic disease.

AP-1 Expression and its Clinical Relevance in Immune Disorders and Cancer

The inflammatory response is known to have a significant role in certain autoimmune diseases and malignancies. We review current knowledge regarding the functions of activator protein 1 (AP-1) as an important modulator in several immune disorders and carcinomas. AP-1 is overexpressed in rheumatoid arthritis and in long-term allogeneic hematopoietic stem cell transplantation survivors; however, decreased expression of AP-1 has been observed in psoriasis, systematic lupus erythematosus and in patients who do not survive after hematopoietic stem cell transplantation. AP-1 also is implicated in the control of various cancer cells. Higher levels of AP-1 components are present in breast and endometrial carcinomas, colorectal cancer and in acute myeloid leukemia, Hodgkin׳s lymphoma and anaplastic large cell lymphoma, with downregulation in ovarian and gastric carcinomas and in patients with chronic myelogenous leukemia. AP-1 may enable the development of helpful markers to identify early-stage disease or to predict severity.

Radiation and SN38 treatments modulate the expression of microRNAs, cytokines and chemokines in colon cancer cells in a p53-directed manner

Aberrant expression of miRNAs, cytokines and chemokines are involved in pathogenesis of colon cancer. However, the expression of p53 mediated miRNAs, cyto- and chemokines after radiation and SN38 treatment in colon cancer remains elusive. Here, human colon cancer cells, HCT116 with wild-type, heterozygous and a functionally null p53, were treated by radiation and SN38. The expression of 384 miRNAs was determined by using the TaqMan® miRNA array, and the expression of cyto- and chemokines was analyzed by Meso-Scale-Discovery instrument. Up- or down-regulations of miRNAs after radiation and SN38 treatments were largely dependent on p53 status of the cells. Cytokines, IL-6, TNF-α, IL-1β, Il-4, IL-10, VEGF, and chemokines, IL-8, MIP-1α were increased, and IFN-γ expression was decreased after radiation, whereas, IL-6, IFN-γ, TNF-α, IL-1β, Il-4, IL-10, IL-8 were decreased, and VEGF and MIP-1α were increased after SN38 treatment. Bioinformatic analysis pointed out that the highly up-regulated miRNAs, let-7f-5p, miR-455-3p, miR-98, miR-155-5p and the down-regulated miRNAs, miR-1, miR-127-5p, miR-142-5p, miR-202-5p were associated with colon cancer pathways and correlated with cyto- or chemokine expression. These miRNAs have the potential for use in colon cancer therapy as they are related to p53, pro- or anti-inflammatory cyto- or chemokines after the radiation and SN38 treatment.

Scan for Motifs: a webserver for the analysis of post-transcriptional regulatory elements in the 3' untranslated regions (3' UTRs) of mRNAs

Background

Gene expression in vertebrate cells may be controlled post-transcriptionally through regulatory elements in mRNAs. These are usually located in the untranslated regions (UTRs) of mRNA sequences, particularly the 3′UTRs.

Results

Scan for Motifs (SFM) simplifies the process of identifying a wide range of regulatory elements on alignments of vertebrate 3′UTRs. SFM includes identification of both RNA Binding Protein (RBP) sites and targets of miRNAs. In addition to searching pre-computed alignments, the tool provides users the flexibility to search their own sequences or alignments. The regulatory elements may be filtered by expected value cutoffs and are cross-referenced back to their respective sources and literature. The output is an interactive graphical representation, highlighting potential regulatory elements and overlaps between them. The output also provides simple statistics and links to related resources for complementary analyses. The overall process is intuitive and fast. As SFM is a free web-application, the user does not need to install any software or databases.

Conclusions

Visualisation of the binding sites of different classes of effectors that bind to 3′UTRs will facilitate the study of regulatory elements in 3′ UTRs.

The antiangiogenic insulin receptor substrate-1 antisense oligonucleotide aganirsen impairs AU-rich mRNA stability by reducing 14-3-3β-tristetraprolin protein complex, reducing inflammation and psoriatic lesion size in patients

Increased inflammation and aberrant angiogenesis underlie psoriasis. Here, we report that the inhibition of insulin receptor substrate-1 (IRS-1) expression with aganirsen resulted in a dose-dependent reduction (P < 0.0001) in IRS-1 protein in the cytoplasm, while IRS-1 protein remained quantitatively unchanged in the perinuclear environment. Aganirsen induced a dose-dependent increase in serine-phosphorylated IRS-1 in the soluble perinuclear-nuclear fraction, inducing IRS-1-14-3-3β protein association (P < 0.001), thereby impairing 14-3-3β-tristetraprolin protein complex and AU-rich mRNA's stability (P < 0.001). Accordingly, aganirsen inhibited (P < 0.001) in vitro the expression of interleukin-8 (IL-8), IL-12, IL-22, and tumor necrosis factor alpha (TNFα), four inflammatory mediators containing mRNA with AU-rich regions. To demonstrate the clinical relevance of this pathway, we tested the efficacy of aganirsen by topical application in a pilot, double-blind, randomized, dose-ranging study in 12 psoriatic human patients. After 6 weeks of treatment, least square mean differences with placebo were -38.9% (95% confidence interval, -75.8 to -2.0%) and -37.4% (-74.3 to -0.5%) at the doses of 0.86 and 1.72 mg/g, respectively. Lesion size reduction was associated with reduced expression of IRS-1 (P < 0.01), TNFα (P < 0.0001), and vascular endothelial growth factor (P < 0.01); reduced keratinocyte proliferation (P < 0.01); and the restoration (P < 0.02) of normal levels of infiltrating CD4(+) and CD3(+) lymphocytes in psoriatic skin lesions. These results suggest that aganirsen is a first-in-class of a new generation of antiangiogenic medicines combining anti-inflammatory activities. Aganirsen-induced downregulation of inflammatory mediators characterized by AU-rich mRNA likely underlies its beneficial clinical outcome in psoriasis. These results justify further large-scale clinical studies to establish the dose of aganirsen and its long-term efficacy in psoriasis.

Utilization of biodegradable polymeric materials as delivery agents in dermatology

Biodegradable polymeric materials are ideal carrier systems for biomedical applications. Features like controlled and sustained delivery, improved drug pharmacokinetics, reduced side effects and safe degradation make the use of these materials very attractive in a lot of medical fields, with dermatology included. A number of studies have shown that particle-based formulations can improve the skin penetration of topically applied drugs. However, for a successful translation of these promising results into a clinical application, a more rational approach is needed to take into account the different properties of diseased skin and the fate of these polymeric materials after topical application. In fact, each pathological skin condition poses different challenges and the way diseased skin interacts with polymeric carriers might be markedly different to that of healthy skin. In most inflammatory skin conditions, the skin's barrier is impaired and the local immune system is activated. A better understanding of such mechanisms has the potential to improve the efficacy of carrier-based dermatotherapy. Such knowledge would allow the informed choice of the type of polymeric carrier depending on the skin condition to be treated, the type of drug to be loaded, and the desired release kinetics. Furthermore, a better control of polymer degradation and release properties in accordance with the skin environment would improve the safety and the selectivity of drug release. This review aims at summarizing the current knowledge on how polymeric delivery systems interact with healthy and diseased skin, giving an overview of the challenges that different pathological skin conditions pose to the development of safer and more specific dermatotherapies.

Expression of miR-155 and miR-126 in situ in cutaneous T-cell lymphoma

Recently, miR-155 has been implicated in cutaneous T-cell lymphoma (CTCL). Thus, elevated levels of miR-155 were observed in skin lesions from CTCL patients as judged from qPCR and micro-array analysis and aberrant, high miR-155 expression was associated with severe disease. Moreover, miR-155 promoted proliferation of malignant T cells in vitro. Little is, however, known about which cell types express miR-155 in vivo in CTCL skin lesions. Here, we study miR-155 expression using in situ hybridization (ISH) with a miR-155 probe, a negative control (scrambled), and a miR-126 probe as a positive control in nine patients with mycosis fungoides, the most frequent subtype of CTCL. We provide evidence that both malignant and non-malignant T cells stain weakly to moderately positive with the miR-155 probe, but generally negative with the miR-126 and negative control probes. Reversely, endothelial cells stain positive for miR-126 and negative for miR-155 and the control probe. Solitary T cells with a malignant morphology display brighter staining with the miR-155 probe. Taken together, our findings suggest that both malignant and non-malignant T cells express miR-155 in situ in CTCL. Moreover, they indicate heterogeneity in miR-155 expression among malignant T cells.

Comparative study of microRNA profiling in keloid fibroblast and annotation of differential expressed microRNAs

Keloids are tumor-like skin scars that grow as a result of the aberrant healing of skin injuries, with no effective treatment. The molecular mechanism underlying keloid pathogenesis is still largely unknown. In this study, we compared microRNA (miRNA) expression profiles between keloid-derived fibroblasts and normal fibroblasts (including fetal and adult dermal fibroblasts) by miRNA microarray analysis. We found that the miRNA profiles in keloid-derived fibroblasts are different with those in normal fibroblasts. Nine miRNAs were differentially expressed, six of which were significantly up-regulated in keloid fibroblasts (KFs), including miR-152, miR-23b-3p, miR-31-5p, miR-320c, miR-30a-5p, and hsv1-miR-H7, and three of which were significantly down-regulated, including miR-4328, miR-145-5p, and miR-143-3p. Functional annotations of differentially expressed miRNA targets revealed that they were enriched in several signaling pathways important for scar wound healing. In conclusion, we demonstrate that the miRNA expression profile is altered in KFs compared with in fetal and adult dermal fibroblasts, and the expression profile may provide a useful clue for exploring the pathogenesis of keloids. miRNAs might partially contribute to the etiology of keloids by affecting several signaling pathways relevant to scar wound healing.

Circulating miRNA biomarkers for Alzheimer's disease

A minimally invasive diagnostic assay for early detection of Alzheimer's disease (AD) is required to select optimal patient groups in clinical trials, monitor disease progression and response to treatment, and to better plan patient clinical care. Blood is an attractive source for biomarkers due to minimal discomfort to the patient, encouraging greater compliance in clinical trials and frequent testing. MiRNAs belong to the class of non-coding regulatory RNA molecules of ∼22 nt length and are now recognized to regulate ∼60% of all known genes through post-transcriptional gene silencing (RNAi). They have potential as useful biomarkers for clinical use because of their stability and ease of detection in many tissues, especially blood. Circulating profiles of miRNAs have been shown to discriminate different tumor types, indicate staging and progression of the disease and to be useful as prognostic markers. Recently their role in neurodegenerative diseases, both as diagnostic biomarkers as well as explaining basic disease etiology has come into focus. Here we report the discovery and validation of a unique circulating 7-miRNA signature (hsa-let-7d-5p, hsa-let-7g-5p, hsa-miR-15b-5p, hsa-miR-142-3p, hsa-miR-191-5p, hsa-miR-301a-3p and hsa-miR-545-3p) in plasma, which could distinguish AD patients from normal controls (NC) with >95% accuracy (AUC of 0.953). There was a >2 fold difference for all signature miRNAs between the AD and NC samples, with p-values<0.05. Pathway analysis, taking into account enriched target mRNAs for these signature miRNAs was also carried out, suggesting that the disturbance of multiple enzymatic pathways including lipid metabolism could play a role in AD etiology.

Regulation of TNF-α with a focus on rheumatoid arthritis

Cytokines and chemokines represent two important groups of proteins that control the human immune system. Dysregulation of the network in which these immunomodulators function can result in uncontrolled inflammation, leading to various diseases including rheumatoid arthritis (RA), characterized by chronic inflammation and bone erosion. Potential triggers of RA include autoantibodies, cytokines and chemokines. The tight regulation of cytokine and chemokine production, and biological activity is important. Tumor necrosis factor-α (TNF-α) is abundantly present in RA patients' serum and the arthritic synovium. This review, therefore, discusses first the role and regulation of the major proinflammatory cytokine TNF-α, in particular the regulation of TNF-α production, post-translational processing and signaling of TNF-α and its receptors. Owing to the important role of TNF-α in RA, the TNF-α-producing cells and the dynamics of its expression, the direct and indirect action of this cytokine and possible biological therapy for RA are described.

Control by a hair's breadth: the role of microRNAs in the skin

MicroRNAs have continued to attract enormous interest in the scientific community ever since their discovery. Their allure stems from their unique role in posttranscriptional gene expression control as well as their potential application as therapeutic targets in various disease pathologies. While much is known concerning their general biological function, such as their interaction with RNA-induced silencing complexes, many important questions still remain unanswered, especially regarding their functions in the skin. In this review, we summarize our current knowledge of the role of microRNAs in the skin in order to shine new light on our understanding of cutaneous biology and emphasize the significance of these small, single-stranded RNA molecules in the largest organ of the human body. Key events in epidermal and hair follicle biology, including differentiation, proliferation, and pigmentation, all involve microRNAs. We explore the role of microRNAs in several cutaneous processes, such as appendage formation, wound-healing, epithelial-mesenchymal transition, carcinogenesis, immune response, and aging. In addition, we discuss current trends in research and offer suggestions for future studies.

Lentiviral vectors for cutaneous RNA managing

Post-transcriptional managing of RNA plays a key role in the intricate network of cellular pathways that regulate our genes. Numerous small RNA species have emerged as crucial regulators of RNA processing and translation. Among these, microRNAs (miRNAs) regulate protein synthesis through specific interactions with target RNAs and are believed to play a role in almost any cellular process and tissue. Skin is no exception, and miRNAs are intensively studied for their role in skin homoeostasis and as potential triggers of disease. For use in skin and many other tissues, therapeutic RNA managing by small RNA technologies is now widely explored. Despite the easy accessibility of skin, the natural barrier properties of skin have challenged genetic intervention studies, and unique tools for studying gene expression and the regulatory role of small RNAs, including miRNAs, in human skin are urgently needed. Human immunodeficiency virus (HIV)-derived lentiviral vectors (LVs) have been established as prominent carriers of foreign genetic cargo. In this review, we describe the use of HIV-derived LVs for efficient gene transfer to skin and establishment of long-term transgene expression in xenotransplanted skin. We outline the status of engineered LVs for delivery of small RNAs and their in vivo applicability for expression of genes and small RNA effectors including small hairpin RNAs, miRNAs and miRNA inhibitors. Current findings suggest that LVs may become key tools in experimental dermatology with particular significance for cutaneous RNA managing and in vivo genetic intervention.

Control of cytokine mRNA expression by RNA-binding proteins and microRNAs

Cytokines are critical mediators of inflammation and host defenses. Regulation of cytokines can occur at various stages of gene expression, including transcription, mRNA export, and post- transcriptional and translational levels. Among these modes of regulation, post-transcriptional regulation has been shown to play a vital role in controlling the expression of cytokines by modulating mRNA stability. The stability of cytokine mRNAs, including TNFα, IL-6, and IL-8, has been reported to be altered by the presence of AU-rich elements (AREs) located in the 3'-untranslated regions (3'UTRs) of the mRNAs. Numerous RNA-binding proteins and microRNAs bind to these 3'UTRs to regulate the stability and/or translation of the mRNAs. Thus, this paper describes the cooperative function between RNA-binding proteins and miRNAs and how they regulate AU-rich elements containing cytokine mRNA stability/degradation and translation. These mRNA control mechanisms can potentially influence inflammation as it relates to oral biology, including periodontal diseases and oral pharyngeal cancer progression.

Interweaving microRNAs and proinflammatory cytokines in gastric mucosa with reference to H. pylori infection

Using endoscopic biopsies, gastric mucosal expression levels of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-alpha (TNF-α) messenger RNA (mRNA) and microRNAs (miRNAs) that were differentially expressed in association with Helicobacter pylori were assessed by quantitative reverse-transcriptase polymerase chain reaction. Among the H. pylori-positive mucosa, 17 out of 29 miRNAs had significant correlations with at least one of the four proinflammatory cytokines in expression. Among the 17 miRNAs, 15 were associated with the degree of neutrophil infiltration and, more prominently, the degree of mononuclear cell infiltration, according to the updated Sydney system. Persistent H. pylori infection may affect the mucosal expression profiles of miRNAs via chronic inflammation mediated by proinflammatory cytokines. There were significant positive correlations between certain miRNAs including the microRNA-200 family and IL-1β, IL-6, or TNF-α mRNA in H. pylori-negative gastric mucosa. Underscoring the causal association between miRNAs and proinflammatory cytokines may provide insights into the pathogenesis of H. pylori-associated gastritis linking to gastric carcinogenesis.