Langerhans Cells-Programmed by the Epidermis

The vaginal microbiome and HIV transmission dynamics

PURPOSE OF REVIEW

Among women, having a nonoptimal, highly diverse vaginal microbiome dominated by bacteria other than optimal Lactobacillus species such as L. crispatus or L. jensenii predicts HIV transmission. Reducing HIV acquisition among women requires a better understanding of the mechanisms through which the vaginal microbiome impacts HIV transmission dynamics and how to more effectively treat and intervene. Technological advancements are improving the ability of researchers to fully characterize interacting host-bacteria mechanisms. Consequently, the purpose of this review was to summarize the most innovative research on the vaginal microbiome and its role in HIV transmission in the past year.

RECENT FINDINGS

Studies combining multiomics, experimental, and translational approaches highlight the associations of a nonoptimal microbiome with maladaptive alterations in immune cell functioning, vaginal metabolites, host cell transcription, mucosal immunity, and epithelial barrier integrity. While there are multiple mechanisms proposed to increase HIV acquisition risk, there are virtually zero acceptable and effective treatments to improve the vaginal microbiome and immunity.

SUMMARY

Women-centered solutions to modify the vaginal microbiome and bacterial metabolites should continue to be explored as a mechanism to reduce HIV acquisition.

The epidemiological and clinical characteristics of Langerhans cell sarcoma in the United States: A population study based on SEER data from 2000 to 2019

Langerhans cell sarcoma (LCS) is a rare aggressive malignancy with a poor prognosis. Our knowledge about this condition is limited and mainly based on case reports, making it challenging to understand its epidemiology, clinical features, and patient outcomes. We conducted a retrospective study of LCS patients diagnosed between 2000 and 2019 using the Surveillance, Epidemiology, and End Results (SEER) database. The data were stratified based on age, race, stage, clinical pattern, and treatment method. Our study found that 57 LCS cases were reported in SEER registries between 2000 and 2019. Among these cases, most patients (50.9%) were over 60 years old and White (71.9%) with almost equal males to females ratio. About 45.6% of cases were localized while 47.4% were at distant stages. Of the patients, 50.9% underwent surgery, 45.6% received chemotherapy, and only 21.1% received radiotherapy. The overall survival rate for patients diagnosed with LCS in the United States is generally low with a 1-year overall rate of 63.8%. Certain factors can negatively impact prognosis, such as advanced stages of the disease, secondary tumors, or more than 1 tumor per patient. LCS is a rare disease with poor survival rates. Future research should incorporate global data for further statistically significant results. Moreover, investigating the molecular, genetic, and pathophysiological backgrounds of these tumors is crucial for developing targeted management strategies and improving prognosis.

Selective Depletion of Staphylococcus aureus Restores the Skin Microbiome and Accelerates Tissue Repair after Injury

Our skin is home to a diverse community of commensal microorganisms integral to cutaneous function. However, microbial dysbiosis and barrier perturbation increase the risk of local and systemic infection. Staphylococcus aureus is a particularly problematic bacterial pathogen, with high levels of antimicrobial resistance and direct association with poor healing outcome. Innovative approaches are needed to selectively kill skin pathogens, such as S aureus, without harming the resident microbiota. In this study, we provide important data on the selectivity and efficacy of an S aureus-targeted endolysin (XZ.700) within the complex living skin/wound microbiome. Initial cross-species comparison using Nanopore long-read sequencing identified the translational potential of porcine rather than murine skin for human-relevant microbiome studies. We therefore performed an interventional study in pigs to assess the impact of endolysin administration on the microbiome. XZ.700 selectively inhibited endogenous porcine S aureus in vivo, restoring microbial diversity and promoting multiple aspects of wound repair. Subsequent mechanistic studies confirmed the importance of this microbiome modulation for effective healing in human skin. Taken together, these findings strongly support further development of S aureus-targeted endolysins for future clinical management of skin and wound infections.

Tonic type 2 immunity is a critical tissue checkpoint controlling autoimmunity in the skin

Immunoregulatory mechanisms established in the lymphoid organs are vital for preventing autoimmunity. However, the presence of similar mechanisms in non-lymphoid tissues remains unclear. Through transcriptomic and lipidomic analyses, we find a negative association between psoriasis and fatty acid metabolism, as well as Th2 signature. Homeostatic expression of liver X receptor (LXR) and peroxisome proliferator-activated receptor gamma (PPARγ) is essential for maintaining fatty acid metabolism and for conferring resistance to psoriasis in mice. Perturbation of signal transducer and activator of transcription 6 (STAT6) diminishes the homeostatic levels of LXR and PPARγ. Furthermore, mice lacking STAT6, interleukin 4 receptor alpha (IL-4Rα), or IL-13, but not IL-4, exhibit increased susceptibility to psoriasis. Under steady state, innate lymphoid cells (ILCs) are the primary producers of IL-13. In human skin, inhibiting tonic type 2 immunity exacerbates psoriasis-like inflammation and IL-17A, while activating LXR or PPARγ inhibits them. Hence, we propose that tonic type 2 immunity, driven by IL-13-producing ILCs, represents a crucial tissue checkpoint that represses autoimmunity and maintains lipid homeostasis in the skin.

The evaluation of skin sensitization potential of the UVCB substance diisopentyl phthalate by in silico and in vitro methods

Diisopentyl phthalate (DiPeP) is primarily used as a plasticizer or additive within the production of polyvinyl chloride (PVC), and has many additional industrial applications. Its metabolites were recently found in urinary samples of pregnant women; thus, this substance is of concern as relates to human exposure. Depending upon the nature of the alcohol used in its synthesis, DiPeP may exist either as a mixture consisting of several branched positional isomers, or as a single defined structure. This article investigates the skin sensitization potential and immunomodulatory effects of DiPeP CAS No. 84777-06-0, which is currently marketed and classified as a UVCB substance, by in silico and in vitro methods. Our findings showed an immunomodulatory effect for DiPeP in LPS-induced THP-1 activation assay (increased CD54 expression). In silico predictions using QSAR TOOLBOX 4.5, ToxTree, and VEGA did not identify DiPeP, in the form of a discrete compound, as a skin sensitizer. The keratinocyte activation (Key Event 2 (KE2) of the adverse outcome pathway (AOP) for skin sensitization) was evaluated by two different test methods (HaCaT assay and RHE assay), and results were discordant. While the HaCaT assay showed that DiPeP can activate keratinocytes (increased levels of IL-6, IL-8, IL-1α, and ILA gene expression), in the RHE assay, DiPeP slightly increased IL-6 release. Although inconclusive for KE2, the role of DiPeP in KE3 (dendritic cell activation) was demonstrated by the increased levels of CD54 and IL-8 and TNF-α in THP-1 cells (THP-1 activation assay). Altogether, findings were inconclusive regarding the skin sensitization potential of the UVCB DiPeP-disagreeing with the results of DiPeP in the form of discrete compound (skin sensitizer by the LLNA assay). Additional studies are needed to elucidate the differences between DiPeP isomer forms, and to better understand the applicability domains of non-animal methods in identifying skin sensitization hazards of UVCB substances.

Why making smoking cessation a priority for rare interstitial lung disease smokers?

This review aims to discuss the complex relationship between smoking and interstitial lung diseases (ILDs), emphasizing the significant morbidity and mortality associated with these conditions. While the etiology of ILDs remains multifactorial, cigarette smoking emerges as a prominent modifiable risk factor implicated in their pathogenesis and progression. This narrative review will provide insight into smoking-associated interstitial lung diseases and personalised approaches to smoking cessation. Epidemiological studies consistently link smoking to ILDs such as idiopathic pulmonary fibrosis (IPF), respiratory bronchiolitis-associated ILD (RB-ILD), and desquamative interstitial pneumonia (DIP), highlighting the urgent need for comprehensive tobacco cessation strategies. Despite the established benefits of smoking cessation, adherence to cessation programs remains challenging due to nicotine addiction, psychological factors, and social influences. The modest success rates of smoking cessation in ILD patients, emphasises the importance of tailored interventions and ongoing support is needed to overcome barriers and to improve outcomes of quitting smoking in this category of vulnerable patients.

Rho-associated kinase regulates Langerhans cell morphology and responsiveness to tissue damage

Skin damage requires efficient immune cell responses to restore organ function. Epidermal-resident immune cells known as Langerhans cells use dendritic protrusions to surveil the skin microenvironment, which contains keratinocytes and peripheral axons. The mechanisms governing Langerhans cell dendrite dynamics and responses to tissue damage are poorly understood. Using skin explants from adult zebrafish, we show that Langerhans cells maintain normal surveillance following axonal degeneration and use their dendrites to engulf small axonal debris. By contrast, a ramified-to-rounded shape transition accommodates the engulfment of larger keratinocyte debris. We find that Langerhans cell dendrites are populated with actin and sensitive to a broad-spectrum actin inhibitor. We show that Rho-associated kinase (ROCK) inhibition leads to elongated dendrites, perturbed clearance of large debris, and reduced Langerhans cell migration to epidermal wounds. Our work describes the dynamics of Langerhans cells and involvement of the ROCK pathway in immune cell responses.

Macrophage Functions in Psoriasis: Lessons from Mouse Models

Psoriasis is a systemic autoimmune/autoinflammatory disease that can be well studied in established mouse models. Skin-resident macrophages are classified into epidermal Langerhans cells and dermal macrophages and are involved in innate immunity, orchestration of adaptive immunity, and maintenance of tissue homeostasis due to their ability to constantly shift their phenotype and adapt to the current microenvironment. Consequently, both macrophage populations play dual roles in psoriasis. In some circumstances, pro-inflammatory activated macrophages and Langerhans cells trigger psoriatic inflammation, while in other cases their anti-inflammatory stimulation results in amelioration of the disease. These features make macrophages interesting candidates for modern therapeutic strategies. Owing to the significant progress in knowledge, our review article summarizes current achievements and indicates future research directions to better understand the function of macrophages in psoriasis.

Extracellular Matrix-Bioinspired Anisotropic Topographical Cues of Electrospun Nanofibers: A Strategy of Wound Healing through Macrophage Polarization

The skin serves as the body's outermost barrier and is the largest organ, providing protection not only to the body but also to various internal organs. Owing to continuous exposure to various external factors, it is susceptible to damage that can range from simple to severe, including serious types of wounds such as burns or chronic wounds. Macrophages play a crucial role in the entire wound-healing process and contribute significantly to skin regeneration. Initially, M1 macrophages infiltrate to phagocytose bacteria, debris, and dead cells in fresh wounds. As tissue repair is activated, M2 macrophages are promoted, reducing inflammation and facilitating restoration of the dermis and epidermis to regenerate the tissue. This suggests that extracellular matrix (ECM) promotes cell adhesion, proliferation, migrationand macrophage polarization. Among the numerous strategies, electrospinning is a versatile technique for obtaining ECM-mimicking structures with anisotropic and isotropic topologies of micro/nanofibers. Various electrospun biomaterials influence macrophage polarization based on their isotropic or anisotropic topologies. Moreover, these fibers possess a high surface-area-to-volume ratio, promoting the effective exchange of vital nutrients and oxygen, which are crucial for cell viability and tissue regeneration. Micro/nanofibers with diverse physical and chemical properties can be tailored to polarize macrophages toward skin regeneration and wound healing, depending on specific requirements. This review describes the significance of micro/nanostructures for activating macrophages and promoting wound healing.

Biofabrication Directions in Recapitulating the Immune System-on-a-Chip

Ever since the implementation of microfluidics in the biomedical field, in vitro models have experienced unprecedented progress that has led to a new generation of highly complex miniaturized cell culture platforms, known as Organs-on-a-Chip (OoC). These devices aim to emulate biologically relevant environments, encompassing perfusion and other mechanical and/or biochemical stimuli, to recapitulate key physiological events. While OoCs excel in simulating diverse organ functions, the integration of the immune organs and immune cells, though recent and challenging, is pivotal for a more comprehensive representation of human physiology. This comprehensive review covers the state of the art in the intricate landscape of immune OoC models, shedding light on the pivotal role of biofabrication technologies in bridging the gap between conceptual design and physiological relevance. The multifaceted aspects of immune cell behavior, crosstalk, and immune responses that are aimed to be replicated within microfluidic environments, emphasizing the need for precise biomimicry are explored. Furthermore, the latest breakthroughs and challenges of biofabrication technologies in immune OoC platforms are described, guiding researchers toward a deeper understanding of immune physiology and the development of more accurate and human predictive models for a.o., immune-related disorders, immune development, immune programming, and immune regulation.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.

Exploring Skin Wound Healing Models and the Impact of Natural Lipids on the Healing Process

Cutaneous wound healing is a complex biological process involving a series of well-coordinated events aimed at restoring skin integrity and function. Various experimental models have been developed to study the mechanisms underlying skin wound repair and to evaluate potential therapeutic interventions. This review explores the diverse array of skin wound healing models utilized in research, ranging from rodent excisional wounds to advanced tissue engineering constructs and microfluidic platforms. More importantly, the influence of lipids on the wound healing process is examined, emphasizing their role in enhancing barrier function restoration, modulating inflammation, promoting cell proliferation, and promoting remodeling. Lipids, such as phospholipids, sphingolipids, and ceramides, play crucial roles in membrane structure, cell signaling, and tissue repair. Understanding the interplay between lipids and the wound microenvironment provides valuable insights into the development of novel therapeutic strategies for promoting efficient wound healing and tissue regeneration. This review highlights the significance of investigating skin wound healing models and elucidating the intricate involvement of lipids in the healing process, offering potential avenues for improving clinical outcomes in wound management.

Biomaterials for immunomodulation in wound healing

The substantial economic impact of non-healing wounds, scarring, and burns stemming from skin injuries is evident, resulting in a financial burden on both patients and the healthcare system. This review paper provides an overview of the skin's vital role in guarding against various environmental challenges as the body's largest protective organ and associated developments in biomaterials for wound healing. We first introduce the composition of skin tissue and the intricate processes of wound healing, with special attention to the crucial role of immunomodulation in both acute and chronic wounds. This highlights how the imbalance in the immune response, particularly in chronic wounds associated with underlying health conditions such as diabetes and immunosuppression, hinders normal healing stages. Then, this review distinguishes between traditional wound-healing strategies that create an optimal microenvironment and recent peptide-based biomaterials that modulate cellular processes and immune responses to facilitate wound closure. Additionally, we highlight the importance of considering the stages of wounds in the healing process. By integrating advanced materials engineering with an in-depth understanding of wound biology, this approach holds promise for reshaping the field of wound management and ultimately offering improved outcomes for patients with acute and chronic wounds.

Fourth dose of microneedle array patch of SARS-CoV-2 S1 protein subunit vaccine elicits robust long-lasting humoral responses in mice

The COVID-19 pandemic has underscored the pressing need for safe and effective booster vaccines, particularly in considering the emergence of new SARS-CoV-2 variants and addressing vaccine distribution inequalities. Dissolving microneedle array patches (MAP) offer a promising delivery method, enhancing immunogenicity and improving accessibility through the skin's immune potential. In this study, we evaluated a microneedle array patch-based S1 subunit protein COVID-19 vaccine candidate, which comprised a bivalent formulation targeting the Wuhan and Beta variant alongside a monovalent Delta variant spike proteins in a murine model. Notably, the second boost of homologous bivalent MAP-S1(WU + Beta) induced a 15.7-fold increase in IgG endpoint titer, while the third boost of heterologous MAP-S1RS09Delta yielded a more modest 1.6-fold increase. Importantly, this study demonstrated that the administration of four doses of the MAP vaccine induced robust and long-lasting immune responses, persisting for at least 80 weeks. These immune responses encompassed various IgG isotypes and remained statistically significant for one year. Furthermore, neutralizing antibodies against multiple SARS-CoV-2 variants were generated, with comparable responses observed against the Omicron variant. Overall, these findings emphasize the potential of MAP-based vaccines as a promising strategy to combat the evolving landscape of COVID-19 and to deliver a safe and effective booster vaccine worldwide.

A systematic overview of metal nanoparticles as alternative disinfectants for emerging SARS-CoV-2 variants

Coronaviruses are a diverse family of viruses, and new strains can emerge. While the majority of coronavirus strains cause mild respiratory illnesses, a few are responsible for severe diseases such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). SARS-CoV-2, the virus responsible for COVID-19, is an example of a coronavirus that has led to a pandemic. Coronaviruses can mutate over time, potentially leading to the emergence of new variants. Some of these variants may have increased transmissibility or resistance to existing vaccines and treatments. The emergence of the COVID-19 pandemic in the recent past has sparked innovation in curbing virus spread, with sanitizers and disinfectants taking center stage. These essential tools hinder pathogen dissemination, especially for unvaccinated or rapidly mutating viruses. The World Health Organization supports the use of alcohol-based sanitizers and disinfectants globally against pandemics. However, there are ongoing concerns about their widespread usage and their potential impact on human health, animal well-being, and ecological equilibrium. In this ever-changing scenario, metal nanoparticles hold promise in combating a range of pathogens, including SARS-CoV-2, as well as other viruses such as norovirus, influenza, and HIV-1. This review explores their potential as non-alcoholic champions against SARS-CoV-2 and other pandemics of tomorrow. This extends beyond metal nanoparticles and advocates a balanced examination of pandemic control tools, exploring their strengths and weaknesses. The manuscript thus involves the evaluation of metal nanoparticle-based alternative approaches as hand sanitizers and disinfectants, providing a comprehensive perspective on this critical issue.

Hydrogels and Wound Healing: Current and Future Prospects

The care and rehabilitation of acute and chronic wounds have a significant social and economic impact on patients and global health. This burden is primarily due to the adverse effects of infections, prolonged recovery, and the associated treatment costs. Chronic wounds can be treated with a variety of approaches, which include surgery, negative pressure wound therapy, wound dressings, and hyperbaric oxygen therapy. However, each of these strategies has an array of limitations. The existing dry wound dressings lack functionality in promoting wound healing and exacerbating pain by adhering to the wound. Hydrogels, which are commonly polymer-based and swell in water, have been proposed as potential remedies due to their ability to provide a moist environment that facilitates wound healing. Their unique composition enables them to absorb wound exudates, exhibit shape adaptability, and be modified to incorporate active compounds such as growth factors and antibacterial compounds. This review provides an updated discussion of the leading natural and synthetic hydrogels utilized in wound healing, details the latest advancements in hydrogel technology, and explores alternate approaches in this field. Search engines Scopus, PubMed, Science Direct, and Web of Science were utilized to review the advances in hydrogel applications over the last fifteen years.

The Current Status and Future Direction of Extracellular Nano-vesicles in the Alleviation of Skin Disorders

Exosomes are extracellular vesicles (EVs) that originate from endocytic membranes. The transfer of biomolecules and biological compounds such as enzymes, proteins, RNA, lipids, and cellular waste disposal through exosomes plays an essential function in cell-cell communication and regulation of pathological and physiological processes in skin disease. The skin is one of the vital organs that makes up about 8% of the total body mass. This organ consists of three layers, epidermis, dermis, and hypodermis that cover the outer surface of the body. Heterogeneity and endogeneity of exosomes is an advantage that distinguishes them from nanoparticles and liposomes and leads to their widespread usage in the remedy of dermal diseases. The biocompatible nature of these extracellular vesicles has attracted the attention of many health researchers. In this review article, we will first discuss the biogenesis of exosomes, their contents, separation methods, and the advantages and disadvantages of exosomes. Then we will highlight recent developments related to the therapeutic applications of exosomes in the treatment of common skin disorders like atopic dermatitis, alopecia, epidermolysis bullosa, keloid, melanoma, psoriasis, and systemic sclerosis.

Molecular Characteristics, Functional Definitions, and Regulatory Mechanisms for Cross-Presentation Mediated by the Major Histocompatibility Complex: A Comprehensive Review

The major histocompatibility complexes of vertebrates play a key role in the immune response. Antigen-presenting cells are loaded on MHC I molecules, which mainly present endogenous antigens; when MHC I presents exogenous antigens, this is called cross-presentation. The discovery of cross-presentation provides an important theoretical basis for the study of exogenous antigens. Cross-presentation is a complex process in which MHC I molecules present antigens to the cell surface to activate CD8+ T lymphocytes. The process of cross-representation includes many components, and this article briefly outlines the origins and development of MHC molecules, gene structures, functions, and their classical presentation pathways. The cross-presentation pathways of MHC I molecules, the cell lines that support cross-presentation, and the mechanisms of MHC I molecular transporting are all reviewed. After more than 40 years of research, the specific mechanism of cross-presentation is still unclear. In this paper, we summarize cross-presentation and anticipate the research and development prospects for cross-presentation.

A critical assessment of the cellular defences of the avian respiratory system: are birds in general and poultry in particular relatively more susceptible to pulmonary infections/afflictions?

In commercial poultry farming, respiratory diseases cause high morbidities and mortalities, begetting colossal economic losses. Without empirical evidence, early observations led to the supposition that birds in general, and poultry in particular, have weak innate and adaptive pulmonary defences and are therefore highly susceptible to injury by pathogens. Recent findings have, however, shown that birds possess notably efficient pulmonary defences that include: (i) a structurally complex three-tiered airway arrangement with aerodynamically intricate air-flow dynamics that provide efficient filtration of inhaled air; (ii) a specialised airway mucosal lining that comprises air-filtering (ciliated) cells and various resident phagocytic cells such as surface and tissue macrophages, dendritic cells and lymphocytes; (iii) an exceptionally efficient mucociliary escalator system that efficiently removes trapped foreign agents; (iv) phagocytotic atrial and infundibular epithelial cells; (v) phagocytically competent surface macrophages that destroy pathogens and injurious particulates; (vi) pulmonary intravascular macrophages that protect the lung from the vascular side; and (vii) proficiently phagocytic pulmonary extravasated erythrocytes. Additionally, the avian respiratory system rapidly translocates phagocytic cells onto the respiratory surface, ostensibly from the subepithelial space and the circulatory system: the mobilised cells complement the surface macrophages in destroying foreign agents. Further studies are needed to determine whether the posited weak defence of the avian respiratory system is a global avian feature or is exclusive to poultry. This review argues that any inadequacies of pulmonary defences in poultry may have derived from exacting genetic manipulation(s) for traits such as rapid weight gain from efficient conversion of food into meat and eggs and the harsh environmental conditions and severe husbandry operations in modern poultry farming. To reduce pulmonary diseases and their severity, greater effort must be directed at establishment of optimal poultry housing conditions and use of more humane husbandry practices.

Straight to the point: targeted mRNA-delivery to immune cells for improved vaccine design

With the deepening of our understanding of adaptive immunity at the cellular and molecular level, targeting antigens directly to immune cells has proven to be a successful strategy to develop innovative and potent vaccines. Indeed, it offers the potential to increase vaccine potency and/or modulate immune response quality while reducing off-target effects. With mRNA-vaccines establishing themselves as a versatile technology for future applications, in the last years several approaches have been explored to target nanoparticles-enabled mRNA-delivery systems to immune cells, with a focus on dendritic cells. Dendritic cells (DCs) are the most potent antigen presenting cells and key mediators of B- and T-cell immunity, and therefore considered as an ideal target for cell-specific antigen delivery. Indeed, improved potency of DC-targeted vaccines has been proved in vitro and in vivo. This review discusses the potential specific targets for immune system-directed mRNA delivery, as well as the different targeting ligand classes and delivery systems used for this purpose.

Microneedle-Mediated Immunization Promotes Lung CD8+ T-Cell Immunity

Microneedle array has proven more efficient in stimulating humoral immunity than intramuscular vaccination. However, its effectiveness in inducing pulmonary CD8+ T cells remains elusive, which is essential to the frontline defense against pulmonary viral infections such as influenza and COVID-19 viruses. The current investigation reveals that superior CD8+ T-cell responses are elicited by immunization with a microneedle array over intradermal or intramuscular immunization using the model antigen ovalbumin, irrespective of whether or not the antigen is provided in the lung. Mechanistically, microneedle array-mediated immunization targeted the epidermal layer and stimulated predominantly Langerhans cells, resulting in increased expression of α4β1 adhesion molecules on the CD8+ T-cell surface, which may play a role in T-cell homing to the lung, whereas CD8+ T cells induced by intramuscular immunization did not express the adhesion molecule sufficiently. CD8+ T cells with a lung-homing propensity were also seen after intradermal vaccination, yet to a much lesser extent. Accordingly, microneedle array immunization provided stronger protection against influenza viral infection than intradermal or intramuscular immunization. The observations offer insights into a strong cross-talk between epidermal immunization and lung immunity and are valuable for designing and delivering vaccines against respiratory viral infections.

Advances in Targeted Therapy for the Treatment of Cervical Cancer

Cervical cancer is an international public health crisis, affecting several hundred thousand women annually. While not universally protective due to other risk factors, many such cases are preventable with vaccination against high-risk serotypes of the human papilloma virus (HPV 6, 11, 16, 18, 31, 33, 45, 53, 58). Advanced-stage and recurrent cervical cancers are typically lethal and have been the focus in recent years of the integration of immune checkpoint inhibitors (CPIs) to improve survival. We have consolidated information regarding the role of the immune system in both disease progression and disease clearance with the aid of targeted therapies and immunotherapeutic agents. Additionally, we have characterized the treatment modalities currently indicated as the standard of care-such as bevacizumab and the immune CPIs-and those recently approved or in development, including Tivdak, Vigil, and chimeric antigen receptor (CAR) T-cells.

Rho-associated kinase regulates Langerhans cell morphology and responsiveness to tissue damage

Skin is often the first physical barrier to encounter invading pathogens and physical damage. Damage to the skin must be resolved quickly and efficiently to maintain organ homeostasis. Epidermal-resident immune cells known as Langerhans cells use dendritic protrusions to dynamically surveil the skin microenvironment, which contains epithelial keratinocytes and somatosensory peripheral axons. The mechanisms governing Langerhans cell dendrite dynamics and responses to tissue damage are not well understood. Using skin explants from adult zebrafish, we show that Langerhans cells maintain normal surveillance activity following axonal degeneration and use their dynamic dendrites to engulf small axonal debris. By contrast, a ramified-to-rounded shape transition accommodates the engulfment of larger keratinocyte debris. We find that Langerhans cell dendrites are richly populated with actin and sensitive to a broad spectrum actin inhibitor. We further show that Rho-associated kinase (ROCK) inhibition leads to elongated dendrites, perturbed clearance of large debris, and reduced Langerhans cell migration to tissue-scale wounds. Altogether, our work describes the unique dynamics of Langerhans cells and involvement of the ROCK pathway in immune cell responses to damage of varying magnitude.

Ovol1/2 loss-induced epidermal defects elicit skin immune activation and alter global metabolism

Skin epidermis constitutes the outer permeability barrier that protects the body from dehydration, heat loss, and myriad external assaults. Mechanisms that maintain barrier integrity in constantly challenged adult skin and how epidermal dysregulation shapes the local immune microenvironment and whole-body metabolism remain poorly understood. Here, we demonstrate that inducible and simultaneous ablation of transcription factor-encoding Ovol1 and Ovol2 in adult epidermis results in barrier dysregulation through impacting epithelial-mesenchymal plasticity and inflammatory gene expression. We find that aberrant skin immune activation then ensues, featuring Langerhans cell mobilization and T cell responses, and leading to elevated levels of secreted inflammatory factors in circulation. Finally, we identify failure to gain body weight and accumulate body fat as long-term consequences of epidermal-specific Ovol1/2 loss and show that these global metabolic changes along with the skin barrier/immune defects are partially rescued by immunosuppressant dexamethasone. Collectively, our study reveals key regulators of adult barrier maintenance and suggests a causal connection between epidermal dysregulation and whole-body metabolism that is in part mediated through aberrant immune activation.

Advanced In Vitro Three-Dimensional Skin Models of Atopic Dermatitis

Atopic dermatitis (AD) is one of the most prevalent inflammatory skin diseases that is characterized by eczematous rashes, intense itching, dry skin, and sensitive skin. Although AD significantly impacts the quality of life and the number of patients keeps increasing, its pathological mechanism is still unknown because of its complexity. The importance of developing new in vitro three-dimensional (3D) models has been underlined in order to understand the mechanisms for the development of therapeutics since the limitations of 2D models or animal models have been repeatedly reported. Thus, the new in vitro AD models should not only be created in 3D structure, but also reflect the pathological characteristics of AD, which are known to be associated with Th2-mediated inflammatory responses, epidermal barrier disruption, increased dermal T-cell infiltration, filaggrin down-regulation, or microbial imbalance. In this review, we introduce various types of in vitro skin models including 3D culture methods, skin-on-a-chips, and skin organoids, as well as their applications to AD modeling for drug screening and mechanistic studies.

Harnessing Biomaterials to Study and Direct Antigen-Specific Immunotherapy

Immunotherapies are an evolving treatment paradigm for addressing cancer, autoimmunity, and infection. While exciting, most of the existing therapies are limited by their specificity─unable to differentiate between healthy and diseased cells at an antigen-specific level. Biomaterials are a powerful tool that enable the development of next-generation immunotherapies due to their tunable synthesis properties. Our lab harnesses biomaterials as tools to study antigen-specific immunity and as technologies to enable new therapeutic vaccines and immunotherapies to combat cancer, autoimmunity, and infections. Our efforts have spanned the study of intrinsic immune profiles of biomaterials, development of novel nanotechnologies assembled entirely from immune cues, manipulation of innate immune signaling, and advanced technologies to direct and control specialized immune niches such as skin and lymph nodes.

Precision Vaccinology Approaches for the Development of Adjuvanted Vaccines Targeted to Distinct Vulnerable Populations

Infection persists as one of the leading global causes of morbidity and mortality, with particular burden at the extremes of age and in populations who are immunocompromised or suffer chronic co-morbid diseases. By focusing discovery and innovation efforts to better understand the phenotypic and mechanistic differences in the immune systems of diverse vulnerable populations, emerging research in precision vaccine discovery and development has explored how to optimize immunizations across the lifespan. Here, we focus on two key elements of precision vaccinology, as applied to epidemic/pandemic response and preparedness, including (a) selecting robust combinations of adjuvants and antigens, and (b) coupling these platforms with appropriate formulation systems. In this context, several considerations exist, including the intended goals of immunization (e.g., achieving immunogenicity versus lessening transmission), reducing the likelihood of adverse reactogenicity, and optimizing the route of administration. Each of these considerations is accompanied by several key challenges. On-going innovation in precision vaccinology will expand and target the arsenal of vaccine components for protection of vulnerable populations.

Cellular activation pathways and interaction networks in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is an evolving field of reconstructive surgery that has revolutionized the treatment of patients with devastating injuries, including those with limb losses or facial disfigurement. The transplanted units are typically comprised of different tissue types, including skin, mucosa, blood and lymphatic vasculature, muscle, and bone. It is widely accepted that the antigenicity of some VCA components, such as skin, is particularly potent in eliciting a strong recipient rejection response following transplantation. The fine line between tolerance and rejection of the graft is orchestrated by different cell types, including both donor and recipient-derived lymphocytes, macrophages, and other immune and donor-derived tissue cells (e.g., endothelium). Here, we delineate the role of different cell and tissue types during VCA rejection. Rejection of VCA grafts and the necessity of life-long multidrug immunosuppression remains one of the major challenges in this field. This review sheds light on recent developments in decoding the cellular signature of graft rejection in VCA and how these may, ultimately, influence the clinical management of VCA patients by way of novel therapies that target specific cellular processes.

Microneedle technology for potential SARS-CoV-2 vaccine delivery

INTRODUCTION

Microneedle fabrication was conceptualised in the 1970s as devices for painless transdermal drug delivery. The last two decades have seen considerable research and financial investment in this area with SARS-CoV-2 and other vaccines catalysing their application to in vivo intradermal vaccine delivery. Microneedle arrays have been fabricated in different shapes, geometries, formats, and out of different materials.

AREAS COVERED

The recent pandemic has offered microneedle platforms the opportunity to be employed as a vehicle for SARS-CoV-2 vaccine administration. The various modes of vaccination delivery and the potential of microneedle arrays-based vaccines will be presented, with a specific focus placed on recent SARS-CoV-2 research. The advantages of microneedle-based vaccine administration, in addition to the major hurdles to their en masse implementation, will be examined.

EXPERT OPINION

Considering the widely acknowledged disadvantages of current vaccine delivery, such as anxiety, pain, and the requirement for professional administration, a large shift in this research sphere is imminent. The SARS-CoV-2 pandemic has catalysed the development of alternate vaccination platforms, working to avoid the requirement for mass vaccination centres. As microneedle vaccine patches are transitioning through clinical study phases, research will be required to ready this technology for a more mass production environment.

Recapitulating Antioxidant and Antibacterial Compounds into a Package for Tissue Regeneration: Dual Function Materials with Synergistic Effect

Oxidative damage and infection can prevent or delay tissue repair. Moreover, infection reinforces reactive oxygen species (ROS) formation, which makes the wound's condition even worse. Therefore, the need for antioxidant and antibacterial agents is felt for tissue regeneration. There are emerging up-and-coming biomaterials that recapitulate both properties into a package, offering an effective solution to turn the wound back into a healing state. In this article, the principles of antioxidant and antibacterial activity are summarized. The review starts with biological aspects, getting the readers to familiarize themselves with tissue barriers against infection. This is followed by the chemistry and mechanism of action of antioxidant and antibacterial materials (dual function). Eventually, the outlook and challenges are underlined to provide where the dual-function biomaterials are and where they are going in the future. It is expected that the present article inspires the designing of dual-function biomaterials to more advanced levels by providing the fundamentals and comparative points of view and paving the clinical way for these materials.

Exploring the role of mitochondria transfer/transplant and their long-non-coding RNAs in regenerative therapies for skin aging

Advancing age and environmental stressors lead to mitochondrial dysfunction in the skin, inducing premature aging, impaired regeneration, and greater risk of cancer. Cells rely on the communication between the mitochondria and the nucleus by tight regulation of long non-coding RNAs (lncRNAs) to avoid premature aging and maintain healthy skin. LncRNAs act as key regulators of cell proliferation, differentiation, survival, and maintenance of skin structure. However, research on how the lncRNAs are dysregulated during aging and due to stressors is needed to develop therapies to regenerate skin's function and structure. In this article, we discuss how age and environmental stressors may alter lncRNA homeodynamics, compromising cell survival and skin health, and how these factors may become inducers of skin aging. We describe skin cell types and how they depend on mitochondrial function and lncRNAs. We also provide a list of mitochondria localized and nuclear lncRNAs that can serve to better understand skin aging. Using bioinformatic prediction tools, we predict possible functions of lncRNAs based on their subcellular localization. We also search for experimentally determined protein interactions and the biological processes involved. Finally, we provide therapeutic strategies based on gene editing and mitochondria transfer/transplant (AMT/T) to restore lncRNA regulation and skin health. This article offers a unique perspective in understanding and defining the therapeutic potential of mitochondria localized lncRNAs (mt-lncRNAs) and AMT/T to treat skin aging and related diseases.

Localized immune surveillance of primary melanoma in the skin deciphered through executable modeling

While skin is a site of active immune surveillance, primary melanomas often escape detection. Here, we have developed an in silico model to determine the local cross-talk between melanomas and Langerhans cells (LCs), the primary antigen-presenting cells at the site of melanoma development. The model predicts that melanomas fail to activate LC migration to lymph nodes until tumors reach a critical size, which is determined by a positive TNF-α feedback loop within melanomas, in line with our observations of murine tumors. In silico drug screening, supported by subsequent experimental testing, shows that treatment of primary tumors with MAPK pathway inhibitors may further prevent LC migration. In addition, our in silico model predicts treatment combinations that bypass LC dysfunction. In conclusion, our combined approach of in silico and in vivo studies suggests a molecular mechanism that explains how early melanomas develop under the radar of immune surveillance by LC.

Photobiomodulation Controls Keratinocytes Inflammatory Response through Nrf2 and Reduces Langerhans Cells Activation

Photobiomodulation (PBM) is rapidly gaining traction as a valuable tool in dermatology for treating many inflammatory skin conditions using low levels of visible light or near-infrared radiation. However, the physiological regulatory pathways responsible for the anti-inflammatory effect of PBM have not been well defined. Since previous studies showed that nuclear factor-erythroid 2 like 2 (Nrf2) is a master regulator of the skin inflammatory response, we have addressed its role in controlling inflammation by PBM. Primary human keratinocytes (KCs) stimulated with 2,4-dinitrochlorobenzene (DNCB) to mimic pro-inflammatory stress were illuminated with two wavelengths: 660 nm or 520 nm. Both lights significantly reduced the mRNA expression of the DNCB-triggered TNF-α, IL-6, and IL-8 cytokines in KCs, while they enhanced Nrf2 pathway activation. PBM-induced Nrf2 is a key regulator of the inflammatory response in KCs since its absence abolished the regulatory effect of light on cytokines production. Further investigations of the mechanisms contributing to the immunoregulatory effect of PBM in inflamed human skin explants showed that 660 nm light prevented Langerhans cells migration into the dermis, preserving their dendricity, and decreased pro-inflammatory cytokine production compared to the DNCB-treated group. This study is the first to report that the PBM-mediated anti-inflammatory response in KCs is Nrf2-dependent and further support the role of PBM in skin immunomodulation. Therefore, PBM should be considered a promising alternative or complementary therapeutic approach for treating skin-related inflammatory diseases.

Zika Vaccine Microparticles (MPs)-Loaded Dissolving Microneedles (MNs) Elicit a Significant Immune Response in a Pre-Clinical Murine Model

Although the global Zika epidemic in 2015–16 fueled vaccine development efforts, there is no approved Zika vaccine or treatment available to date. Current vaccine platforms in clinical trials are administered via either subcutaneous or intramuscular injections, which are painful and decrease compliance. Therefore, in the present study, we explored Zika vaccine microparticles (MPs)-loaded dissolving microneedles (MNs) with adjuvant MPs encapsulating Alhydrogel® and MPL-A® administered via the transdermal route as a pain-free vaccine strategy. We characterized the MNs for needle length, pore formation, and dissolvability when applied to murine skin. Further, we evaluated the in vivo efficacy of vaccine MPs-loaded MNs with or without adjuvants by measuring the immune response after transdermal immunization. The vaccine MPs-loaded dissolving MNs with adjuvants induced significant IgG, IgG1, and IgG2a titers in immunized mice compared to the untreated control group. After the dosing regimen, the animals were challenged with Zika virus, monitored for seven days, and sacrificed to collect spleen and lymph nodes. The lymphocytes and splenocytes from the immunized mice showed significant expressions of helper (CD4) and cytotoxic (CD8a) cell surface markers compared to the control group. Thus, this study puts forth a ‘proof-of-concept’ for a pain-free transdermal vaccine strategy against Zika.

Transmission of Zika virus by dendritic cell subsets in skin and vaginal mucosa

Zika virus is a member of the Flaviviridae family that has caused recent outbreaks associated with neurological malformations. Transmission of Zika virus occurs primarily via mosquito bite but also via sexual contact. Dendritic cells (DCs) and Langerhans cells (LCs) are important antigen presenting cells in skin and vaginal mucosa and paramount to induce antiviral immunity. To date, little is known about the first cells targeted by Zika virus in these tissues as well as subsequent dissemination of the virus to other target cells. We therefore investigated the role of DCs and LCs in Zika virus infection. Human monocyte derived DCs (moDCs) were isolated from blood and primary immature LCs were obtained from human skin and vaginal explants. Zika virus exposure to moDCs but not skin and vaginal LCs induced Type I Interferon responses. Zika virus efficiently infected moDCs but neither epidermal nor vaginal LCs became infected. Infection of a human full skin model showed that DC-SIGN expressing dermal DCs are preferentially infected over langerin+ LCs. Notably, not only moDCs but also skin and vaginal LCs efficiently transmitted Zika virus to target cells. Transmission by LCs was independent of direct infection of LCs. These data suggest that DCs and LCs are among the first target cells for Zika virus not only in the skin but also the genital tract. The role of vaginal LCs in dissemination of Zika virus from the vaginal mucosa further emphasizes the threat of sexual transmission and supports the investigation of prophylaxes that go beyond mosquito control.

Canvassing Prospects of Glyco-Nanovaccines for Developing Cross-Presentation Mediated Anti-Tumor Immunotherapy

In view of the severe downsides of conventional cancer therapies, the quest of developing alternative strategies still remains of critical importance. In this regard, antigen cross-presentation, usually employed by dendritic cells (DCs), has been recognized as a potential solution to overcome the present impasse in anti-cancer therapeutic strategies. It has been established that an elevated cytotoxic T lymphocyte (CTL) response against cancer cells can be achieved by targeting receptors expressed on DCs with specific ligands. Glycans are known to serve as ligands for C-type lectin receptors (CLRs) expressed on DCs, and are also known to act as a tumor-associated antigen (TAA), and, thus, can be harnessed as a potential immunotherapeutic target. In this scenario, integrating the knowledge of cross-presentation and glycan-conjugated nanovaccines can help us to develop so called 'glyco-nanovaccines' (GNVs) for targeting DCs. Here, we briefly review and analyze the potential of GNVs as the next-generation anti-tumor immunotherapy. We have compared different antigen-presenting cells (APCs) for their ability to cross-present antigens and described the potential nanocarriers for tumor antigen cross-presentation. Further, we discuss the role of glycans in targeting of DCs, the immune response due to pathogens, and imitative approaches, along with parameters, strategies, and challenges involved in cross-presentation-based GNVs for cancer immunotherapy. It is known that the effectiveness of GNVs in eradicating tumors by inducing strong CTL response in the tumor microenvironment (TME) has been largely hindered by tumor glycosylation and the expression of different lectin receptors (such as galectins) by cancer cells. Tumor glycan signatures can be sensed by a variety of lectins expressed on immune cells and mediate the immune suppression which, in turn, facilitates immune evasion. Therefore, a sound understanding of the glycan language of cancer cells, and glycan-lectin interaction between the cancer cells and immune cells, would help in strategically designing the next-generation GNVs for anti-tumor immunotherapy.

Transcutaneous immunization via dissolving microneedles protects mice from lethal influenza H7N9 virus challenge

Avian influenza H7N9 virus has first emerged in 2013 and since then has spread in China in five seasonal waves. In humans, influenza H7N9 virus infection is associated with a high fatality rate; thus, an effective vaccine for this virus is needed. In the present study, we evaluated the usefulness of dissolving microneedles (MNs) loaded with influenza H7N9 vaccine in terms of the dissolution time, insertion capacity, insertion depth, and structural integrity of H7N9 virus in vitro. Our in vitro results showed MNs dissolved within 6 mins. The depth of skin penetration was 270 µm. After coating with a matrix material solution, the H7N9 proteins were agglomerated. We detected the H7N9 delivery time and humoral immune response in vivo. In a mouse model, the antigen retention time was longer for MNs than for intramuscular (IM) injection. The humoral response showed that similar to IM administration, MN administration increased the levels of functional and systematic antibodies and protection against the live influenza A/Anhui/01/2013 virus (Ah01/H7N9). The protection level was determined by the analysis of pathological sections of infected lungs. MN and IM administration yielded results superior to those in the control group. Taken together, these findings demonstrate that the use of dissolving MNs to deliver influenza H7N9 vaccines is a promising immunization approach.

Immunomodulating Hydrogels as Stealth Platform for Drug Delivery Applications

Non-targeted persistent immune activation or suppression by different drug delivery platforms can cause adverse and chronic physiological effects including cancer and arthritis. Therefore, non-toxic materials that do not trigger an immunogenic response during delivery are crucial for safe and effective in vivo treatment. Hydrogels are excellent candidates that can be engineered to control immune responses by modulating biomolecule release/adsorption, improving regeneration of lymphoid tissues, and enhancing function during antigen presentation. This review discusses the aspects of hydrogel-based systems used as drug delivery platforms for various diseases. A detailed investigation on different immunomodulation strategies for various delivery options and deliberate upon the outlook of such drug delivery platforms are conducted.

Soluble mediators in the function of the epidermal-immune-neuro unit in the skin

Skin is the largest, environmentally exposed (barrier) organ, capable of integrating various signals into effective defensive responses. The functional significance of interactions among the epidermis and the immune and nervous systems in regulating and maintaining skin barrier function is only now becoming recognized in relation to skin pathophysiology. This review focuses on newly described pathways that involve soluble mediator-mediated crosstalk between these compartments. Dysregulation of these connections can lead to chronic inflammatory diseases and/or pathologic conditions associated with chronic pain or itch.

Interoperability of RTN1A in dendrite dynamics and immune functions in human Langerhans cells

Skin is an active immune organ where professional antigen-presenting cells such as epidermal Langerhans cells (LCs) link innate and adaptive immune responses. While Reticulon 1A (RTN1A) was recently identified in LCs and dendritic cells in cutaneous and lymphoid tissues of humans and mice, its function is still unclear. Here, we studied the involvement of this protein in cytoskeletal remodeling and immune responses toward pathogens by stimulation of Toll-like receptors (TLRs) in resident LCs (rLCs) and emigrated LCs (eLCs) in human epidermis ex vivo and in a transgenic THP-1 RTN1A+ cell line. Hampering RTN1A functionality through an inhibitory antibody induced significant dendrite retraction of rLCs and inhibited their emigration. Similarly, expression of RTN1A in THP-1 cells significantly altered their morphology, enhanced aggregation potential, and inhibited the Ca2+ flux. Differentiated THP-1 RTN1A+ macrophages exhibited long cell protrusions and a larger cell body size in comparison to wild-type cells. Further, stimulation of epidermal sheets with bacterial lipoproteins (TLR1/2 and TLR2 agonists) and single-stranded RNA (TLR7 agonist) resulted in the formation of substantial clusters of rLCs and a significant decrease of RTN1A expression in eLCs. Together, our data indicate involvement of RTN1A in dendrite dynamics and structural plasticity of primary LCs. Moreover, we discovered a relation between activation of TLRs, clustering of LCs, and downregulation of RTN1A within the epidermis, thus indicating an important role of RTN1A in LC residency and maintaining tissue homeostasis.

Transcriptional programming of immunoregulatory responses in human Langerhans cells

Human epidermal Langerhans cells (LCs) maintain immune homeostasis in the skin. To examine transcriptional programming of human primary LCs during homeostasis, we performed scRNA-seq analysis of LCs before and after migration from the epidermis, coupled with functional assessment of their regulatory T cell priming capabilities. The analysis revealed that steady-state LCs exist in a continuum of maturation states and upregulate antigen presentation genes along with an immunoregulatory module including the genes IDO1, LGALS1, LAMTOR1, IL4I, upon their migration. The migration-induced transition in genomic state is accompanied by the ability of LCs to more efficiently prime regulatory T cell responses in co-culture assays. Computational analyses of the scRNAseq datasets using SCENIC and Partial Information Decomposition in Context identified a set of migration-induced transcription factors including IRF4, KLF6 and RelB as key nodes within a immunoregulatory gene regulatory network. These findings support a model in which efficient priming of immunoregulatory responses by LCs is dependent on coordinated upregulation of a migration-coupled maturation program with a immunoregulation-promoting genomic module.

The modulatory role of dendritic cell-T cell cross-talk in breast cancer: Challenges and prospects

Antigen recognition and presentation are highlighted as the first steps in developing specialized antigen responses. Dendritic cells (DCs) are outstanding professional antigen-presenting cells (APCs) responsible for priming cellular immunity in pathological states, including cancer. However, the diminished or repressed function of DCs is thought to be a substantial mechanism through which tumors escape from the immune system. In this regard, DCs obtained from breast cancer (BC) patients represent a notably weakened potency to encourage specific T-cell responses. Additionally, impaired DC-T-cell cross-talk in BC facilitates the immune evade of cancer cells and is connected with tumor advancement, immune tolerance, and adverse prognosis for patients. In this review we aim to highlight the available knowledge on DC-T-cell interactions in BC aggressiveness and show its therapeutic potential in BC treatment.

Comparative immunogenicity analysis of intradermal versus intramuscular immunization with a recombinant human adenovirus type 5 vaccine against Ebola virus

The proper route for vaccine delivery plays an important role in activating a robust immune response. Several viral vector-based vaccines against Ebola disease administered intramuscularly have been found to have excellent immunogenicity and protectiveness. In this study, we evaluated different vaccine routes for Ad5-EBOV delivery by comparing humoral and cellular responses, germinal center reactions, dendritic cell activation and antigen expression. Mice injected intramuscularly with the vaccine exhibited an advantage in antigen expression, leading to more robust germinal center and humoral responses, while intradermal injection recruited more migrating DCs and induced a more polyfunctional cellular response. Our study provides more data for future use of viral vector-based vaccines.

Association of polymorphous light eruption with NOD-2 and TLR-5 gene polymorphisms

BACKGROUND

Polymorphous light eruption (PLE) is a common, immunologically mediated, photosensitive skin disease. After ultraviolet-B (UV-B) irradiation, patients with PLE show reduced Langerhans cell (LC) depletion in the epidermis, which results in a non-suppressive microenvironment in the skin. Interestingly, severe acute graft-versus-host-disease (aGvHD) occurred in stem cell transplanted patients that showed no or incomplete depletion of LCs after UVB-irradiation. Genetic variation in nucleotide-binding oligomerization domain 2 (NOD-2) and toll-like receptor 5 (TLR-5) genes also confers susceptibility to aGvHD.

OBJECTIVES

We hypothesized that PLE is associated with genetic variation in the NOD-2 and TLR-5 genes.

METHODS

We investigated single nucleotid polymorphisms (SNPs) of NOD-2 (R702W, G908R, 3020Cins) and TLR-5 (A592S, P616L, N392STOP) in skin biopsies of PLE-patients (n=143) and in healthy controls (n=104) using restriction fragment-length polymorphism analysis.

RESULTS

The frequency of NOD-2 alleles with the SNP R702W was significantly higher in PLE than in controls (31.8% vs 6.3%; p<0.0001), and homozygous carriers of this mutation were more common in PLE (27.9% vs 0%; p<0.0001). For SNP 3020Cins, the allele frequency (7.3% vs 0.7%; p=0.0025) and the number of heterozygotes (14.7% vs 1.3%; p=0.0019) were higher in PLE. The frequency of alleles with the N392STOP SNP of the TLR5 gene, which is associated with a truncated, non-functional receptor, was significantly higher in PLE (21% vs 5%; 7% vs 1% homozygotes, 28% vs 8% heterozygotes; p<0.0001). The other SNPs did not differ significantly.

CONCLUSIONS

This study yielded a high frequency of functional SNPs in the NOD-2 and TLR-5 genes in PLE. The same SNPs are associated with aGvHD and there are similarities in the reaction of LCs after UVB-irradiation between aGvHD and PLE. This leads to the hypothesis that PLE-patients may be more susceptible to developing GvHD after stem-cell transplantation, an assumption that needs to be investigated further.

Reprograming the immune niche for skin tissue regeneration - From cellular mechanisms to biomaterials applications

Despite the rapid development of therapeutic approaches for skin repair, chronic wounds such as diabetic foot ulcers remain an unaddressed problem that affects millions of people worldwide. Increasing evidence has revealed the crucial and diverse roles of the immune cells in the development and repair of the skin tissue, prompting new research to focus on further understanding and modulating the local immune niche for comprehensive, 'perfect' regeneration. In this review, we first introduce how different immunocytes and certain stromal cells involved in innate and adaptive immunity coordinate to maintain the immune niche and tissue homeostasis, with emphasis on their specific roles in normal and pathological wound healing. We then discuss novel engineering approaches - particularly biomaterials systems and cellular therapies - to target different players of the immune niche, with three major aims to i) overcome 'under-healing', ii) avoid 'over-healing', and iii) promote functional restoration, including appendage development. Finally, we highlight how these strategies strive to manage chronic wounds and achieve full structural and functional skin recovery by creating desirable 'soil' through modulating the immune microenvironment.

Dual Effect of Immune Cells within Tumour Microenvironment: Pro- and Anti-Tumour Effects and Their Triggers

Our body is constantly exposed to pathogens or external threats, but with the immune response that our body can develop, we can fight off and defeat possible attacks or infections. Nevertheless, sometimes this threat comes from an internal factor. Situations such as the existence of a tumour also cause our immune system (IS) to be put on alert. Indeed, the link between immunology and cancer is evident these days, with IS being used as one of the important targets for treating cancer. Our IS is able to eliminate those abnormal or damaged cells found in our body, preventing the uncontrolled proliferation of tumour cells that can lead to cancer. However, in several cases, tumour cells can escape from the IS. It has been observed that immune cells, the extracellular matrix, blood vessels, fat cells and various molecules could support tumour growth and development. Thus, the developing tumour receives structural support, irrigation and energy, among other resources, making its survival and progression possible. All these components that accompany and help the tumour to survive and to grow are called the tumour microenvironment (TME). Given the importance of its presence in the tumour development process, this review will focus on one of the components of the TME: immune cells. Immune cells can support anti-tumour immune response protecting us against tumour cells; nevertheless, they can also behave as pro-tumoural cells, thus promoting tumour progression and survival. In this review, the anti-tumour and pro-tumour immunity of several immune cells will be discussed. In addition, the TME influence on this dual effect will be also analysed.

Cutaneous leishmaniasis: multiomics approaches to unravel the role of immune cells checkpoints

INTRODUCTION

Cutaneous leishmaniasis (CL) is the most frequent form of leishmaniases, associated with skin inflammation and ulceration. Understanding the interaction of different phagocytic cells in the recognition and uptake of different Leishmania species is critical for controlling the infection. Phagocytic cells have a pivotal role as professional antigen-presenting cells that bridge the innate and adaptive immunity and shape the outcome of the disease.

AREAS COVERED

Here we reviewed new technologies with high-throughput data collection capabilities along with systems biology approaches which are recently being used to decode the paradox of CL immunology.

EXPERT OPINION

We emphasized on the crosstalk between DC and T-cells while focusing on the immune checkpoints interactions between the human immune system and the Leishmania species. Further, we discussed omics technologies including bulk RNA sequencing, reverse transcriptase-multiplex ligation dependent probe amplification (RT-MLPA), and proximity extension assay (PEA) in studies on human blood or tissue-driven samples from CL patients in which we have so far been involved.