Plasmacytoid dendritic cells sense skin injury and promote wound healing through type I interferons

Substantial Effects of Carotenoids on Skin Health: A Mechanistic Perspective

There has been an upsurge in the incidences of skin disorders and their mortalities owing to various environmental, hormonal, and epigenetic risk factors. Melanoma, atopic dermatitis, psoriasis, and photoaging and associated consequences are largely observed in the population globally. The social stigma, economic burden, and adverse effects from chronic medication endured by the patients emphasize the necessity of more effective natural therapeutics. Carotenoids are economically valuable tetraterpenoid pigments synthesized by plants and microorganisms, which play a paramount role in their overall growth and development. Extensive in vitro and in vivo investigations evidenced that phytopigments like carotenoids target multiple intracellular signaling pathways involving the mitogen-activated protein kinases, Janus kinase/signal transducers, and activators of transcription, apoptotic, and autophagy proteins to ameliorate melanoma. Besides, carotenoids curbed the activation and the release of immunoregulatory molecules such as cytokines and chemokines to abrogate skin immune disorders, photoaging, and associated consequences. Here, we provide a holistic discussion on the pathophysiology of prominent skin disorders and the ameliorating effects of carotenoids as evidenced in the in vitro, in vivo, and clinical interventions. We also advocate the requisite of formulating carotenoid medications after extensive clinical interventions and validation for mitigating various skin dysfunctions.

Mechanosensing regulates pDC activation in the skin through NRF2 activation

Plasmacytoid DCs (pDCs) infiltrate the skin, chronically produce type I interferon (IFN-I), and promote skin lesions and fibrosis in autoimmune patients. However, what controls their activation in the skin is unknown. Here, we report that increased stiffness inhibits the production of IFN-I by pDCs. Mechanistically, mechanosensing activates stress pathways including NRF2, which induces the pentose phosphate pathway and reduces pyruvate levels, a product necessary for pDC responses. Modulating NRF2 activity in vivo controlled the pDC response, leading to resolution or chronic induction of IFN-I in the skin. In systemic sclerosis (SSc) patients, although NRF2 was induced in skin-infiltrating pDCs, as compared with blood pDCs, the IFN response was maintained. We observed that CXCL4, a profibrotic chemokine elevated in fibrotic skin, was able to overcome stiffness-mediated IFN-I inhibition, allowing chronic IFN-I responses by pDCs in the skin. Hence, these data identify a novel regulatory mechanism exerted by the skin microenvironment and identify points of dysregulation of this mechanism in patients with skin inflammation and fibrosis.

Advanced Immunomodulatory Biomaterials for Therapeutic Applications

The multifaceted biological defense system modulating complex immune responses against pathogens and foreign materials plays a critical role in tissue homeostasis and disease progression. Recently developed biomaterials that can specifically regulate immune responses, nanoparticles, graphene, and functional hydrogels have contributed to the advancement of tissue engineering as well as disease treatment. The interaction between innate and adaptive immunity, collectively determining immune responses, can be regulated by mechanobiological recognition and adaptation of immune cells to the extracellular microenvironment. Therefore, applying immunomodulation to tissue regeneration and cancer therapy involves manipulating the properties of biomaterials by tailoring their composition in the context of the immune system. This review provides a comprehensive overview of how the physicochemical attributes of biomaterials determine immune responses, focusing on the physical properties that influence innate and adaptive immunity. This review also underscores the critical aspect of biomaterial-based immune engineering for the development of novel therapeutics and emphasizes the importance of understanding the biomaterials-mediated immunological mechanisms and their role in modulating the immune system.

The association between physical trauma and autoimmune articular and dermatological disorders

OBJECTIVE

This review investigates the association between physical trauma and the onset and progression of various inflammatory diseases, including psoriatic arthritis (PsA), rheumatoid arthritis (RA), spondyloarthropathies (SpA), and Familial Mediterranean Fever (FMF). In addition, we will refer to the linkage between physical injury and skin manifestations in patients with psoriasis, sarcoidosis and systemic sclerosis. The aim is to summarize the current evidence and explore the potential mechanisms through which trauma may affect these conditions.

METHODS

A detailed literature review was conducted, focusing on studies linking physical trauma with the development of psoriasis, SpA, PsA, RA, FMF, systemic sclerosis and sarcoidosis. The review includes observational data, case reports, and experimental studies that highlight the impact of trauma on disease initiation and exacerbation.

RESULTS

Physical trauma is implicated in the pathogenesis of several dermatological and rheumatological conditions. Biomechanical stress and microdamage at entheses contribute to the development of SpA. In PsA, trauma is associated with the onset of enthesitis and arthritis, supported by increased prevalence in affected patients and is often regarded as "deep Koebner phenomenon". The Koebner phenomenon links skin trauma with psoriasis, where new lesions appear at injury sites. RA shows a notable association with physical trauma, with retrospective studies suggesting that trauma can trigger disease onset, although the exact mechanisms remain unclear. The concept of the synovio-entheseal complex is discussed in order to elucidate how mechanical stress and immune responses interplay in SpA. Physical exertion or injury might precipitate FMF attacks, though existing data remain limited. Sarcoidosis has been linked to tattoo-related trauma, suggesting a potential role of localized injury in sarcoid-like reactions. Several case reports describe the occurrence of dermatologic manifestations of scleroderma, including morphea in patients with localized disease and perifollicular hypopigmentation in patients with systemic sclerosis.

CONCLUSION

This review consolidates current evidence on the relationship between physical trauma and various inflammatory conditions, emphasizing the need for further research to fully understand these connections. These findings highlight the importance of considering trauma in the clinical management of these diseases and suggest avenues for future investigation.

Cathelicidin antimicrobial peptide expression in neutrophils and neurons antagonistically modulates neuroinflammation

Multiple sclerosis (MS) is an autoimmune disease that affects the CNS, the pathophysiology of which remains unclear and for which there is no definitive cure. Antimicrobial peptides (AMPs) are immunomodulatory molecules expressed in various tissues, including the CNS. Here, we investigated whether the cathelicidin-related AMP (CRAMP) modulated the development of experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We showed that, at an early stage, CNS-recruited neutrophils produced neutrophil extracellular traps (NETs) rich in CRAMP that were required for EAE initiation. NET-associated CRAMP stimulated IL-6 production by dendritic cells via the cGAS/STING pathway, thereby promoting encephalitogenic Th17 response. However, at a later disease stage, neurons also expressed CRAMP that reduced EAE severity. Camp knockdown in neurons led to disease exacerbation, while local injection of CRAMP1-39 at the peak of EAE promoted disease remission. In vitro, CRAMP1-39 regulated the activation of microglia and astrocytes through the formyl peptide receptor (FPR) 2. Finally, administration of butyrate, a gut microbiota-derived metabolite, stimulated the expression of neural CRAMP via the free fatty acids receptors 2/3 (FFAR2/3), and prevented EAE. This study shows that CRAMP produced by different cell types has opposing effects on neuroinflammation, offering therapeutic opportunities for MS and other neuroinflammatory disorders.

Topical Application of Nano-Sized Graphene Oxide Cream Ameliorates Acute Skin Inflammation in Mice

We have previously shown that nano-sized graphene oxide (NGO) displays anti-inflammatory activities against NKT cell-mediated sepsis. To address whether NGO could be applied to treat acute skin inflammation, we developed a conventional skin Cetaphil cream containing NGO (denoted as NGO cream) for topical application to skin lesions and investigated its therapeutic efficacy by employing the tape-stripping-induced acute skin inflammation model. Topical application of NGO cream to the wounded area significantly reduced skin lesions compared with application of the control cream. Moreover, NGO cream treatment prevented the tape-stripping-elicited infiltration of, and IL-1β production by, skin neutrophils and dendritic cells. Furthermore, such anti-inflammatory effects of NGO cream were attributed to decreased infiltration of IL-12-producing dendritic cells and IFNγ-producing cells (eg, CD4+ T, CD8+ T, γδ T, NK, and NKT cells) into the skin. In addition, topical NGO cream administration enhanced the expression of suppressive molecules such as FR4 on skin regulatory T cells. Through RNA-sequencing analysis, we found that the preventive effect of NGO cream on acute skin inflammation may be correlated with the activation of keratinocytes located in the epidermis. Our results support NGO cream as a therapeutic option to control acute skin inflammation.

Paradoxical Psoriasis: An Updated Review of Clinical Features, Pathogenesis, and Treatment Options

The definition of paradoxical psoriasis (PP) encompasses 2 main scenarios, namely, (i) new-onset psoriasis in patients treated for a different disease and (ii) worsening as well as phenotypical change of pre-existing psoriasis. Originally restricted to the appearance of an untoward psoriasiform reaction under TNF inhibitors, the term has gained new meaning, with the progressive observation of psoriasis-like eruptions also with other medications. Although the conceptual framework of PP has expanded, a molecular and clinicotherapeutic classification is still lacking. In addition, a certain degree of confusion surrounds the correct terminology to indicate these eruptions. In this paper, evidence on the epidemiology, clinical features, pathogenesis, and treatment of PP is reviewed, providing a perspective on possible pathogenesis-driven therapeutic approaches.

OLFM4 regulates the antimicrobial and DNA binding activity of neutrophil cationic proteins

Neutrophil cationic proteins (NCPs) are a group of granule antimicrobial and inflammatory proteins released by activated neutrophils. These proteins primarily function via their positively charged structure, which facilitates interactions with bacterial membranes and the formation of immunogenic DNA complexes, thereby contributing to the initiation of wound repair in injured skin. After analyzing the structural properties of secreted neutrophil granule proteins, we identified OLFM4 as the only negatively charged molecule that interferes with NCP oligomerization. Through this interference, OLFM4 can inhibit neutrophil-mediated bacterial killing and DNA complex-dependent activation of Toll-like receptor 9 (TLR9) in plasmacytoid dendritic cells (pDCs) and neutrophils. While addition of exogenous OLFM4 blocks these processes, OLFM4 inhibition enhances neutrophil-dependent bacterial killing and DNA complex formation, ultimately leading to accelerated closure of skin wounds.

Advances in psoriasis research: From pathogenesis to therapeutics

Psoriasis is a chronic inflammatory condition affecting approximately 2 % to 3 % of the global population. The pathogenesis of psoriasis is complex, involving immune dysregulation, hyperproliferation and angiogenesis. It is a multifactorial disease which is influenced by genetic and environmental factors. The development of various therapeutic agents, such as JAK inhibitors, small molecules, and biologics with potential anti-psoriatic properties was possible with the vast understanding of the pathogenesis of psoriasis. Various signalling pathways, including NF-κB, JAK-STAT, S1P, PDE-4, and A3AR that are involved in the pathogenesis of psoriasis as well as the preclinical models utilised in the research of psoriasis have been highlighted in this review. The review also focuses on technological advancements that have contributed to a better understanding of psoriasis. Then, the molecules targeting the respective signalling pathways that are still under clinical trials or recently approved as well as the latest breakthroughs in therapeutic and drug delivery approaches that can contribute to the improvement in the management of psoriasis are highlighted in this review. This review provides an extensive understanding of the current state of research in psoriasis, giving rise to opportunities for researchers to discover future therapeutic breakthroughs and personalised interventions. Efficient treatment options for individuals with psoriasis can be achieved by an extensive understanding of pathogenesis, therapeutic agents, and novel drug delivery strategies.

The role of plasmacytoid dendritic cells (pDCs) in immunity during viral infections and beyond

Type I and III interferons (IFNs) are essential for antiviral immunity and act through two different but complimentary pathways. First, IFNs activate intracellular antimicrobial programs by triggering the upregulation of a broad repertoire of viral restriction factors. Second, IFNs activate innate and adaptive immunity. Dysregulation of IFN production can lead to severe immune system dysfunction. It is thus crucial to identify and characterize the cellular sources of IFNs, their effects, and their regulation to promote their beneficial effects and limit their detrimental effects, which can depend on the nature of the infected or diseased tissues, as we will discuss. Plasmacytoid dendritic cells (pDCs) can produce large amounts of all IFN subtypes during viral infection. pDCs are resistant to infection by many different viruses, thus inhibiting the immune evasion mechanisms of viruses that target IFN production or their downstream responses. Therefore, pDCs are considered essential for the control of viral infections and the establishment of protective immunity. A thorough bibliographical survey showed that, in most viral infections, despite being major IFN producers, pDCs are actually dispensable for host resistance, which is achieved by multiple IFN sources depending on the tissue. Moreover, primary innate and adaptive antiviral immune responses are only transiently affected in the absence of pDCs. More surprisingly, pDCs and their IFNs can be detrimental in some viral infections or autoimmune diseases. This makes the conservation of pDCs during vertebrate evolution an enigma and thus raises outstanding questions about their role not only in viral infections but also in other diseases and under physiological conditions.

TLR9 activation in large wound induces tissue repair and hair follicle regeneration via γδT cells

The mechanisms underlying tissue repair in response to damage have been one of main subjects of investigation. Here we leverage the wound-induced hair neogenesis (WIHN) models in adult mice to explore the correlation between degree of damage and the healing process and outcome. The multimodal analysis, in combination with single-cell RNA sequencing help to explore the difference in wounds of gentle and heavy damage degrees, identifying the potential role of toll-like receptor 9 (TLR9) in sensing the injury and regulating the immune reaction by promoting the migration of γδT cells. The TLR9 deficient mice or wounds injected with TLR9 antagonist have greatly impaired healing and lower WIHN levels. Inhibiting the migration of γδT cells or knockout of γδT cells also suppress the wound healing and regeneration, which can't be rescued by TLR9agonist. Finally, the amphiregulin (AREG) is shown as one of most important effectors secreted by γδT cells and keratinocytes both in silicon or in the laboratory, whose expression influences WIHN levels and the expression of stem cell markers. In total, our findings reveal a previously unrecognized role for TLR9 in sensing skin injury and influencing the tissue repair and regeneration by modulation of the migration of γδT cells, and identify the TLR9-γδT cells-areg axis as new potential targets for enhancing tissue regeneration.

Skin Telocytes Could Fundament the Cellular Mechanisms of Wound Healing in Platelet-Rich Plasma Administration

For more than 40 years, autologous platelet concentrates have been used in clinical medicine. Since the first formula used, namely platelet-rich plasma (PRP), other platelet concentrates have been experimented with, including platelet-rich fibrin and concentrated growth factor. Platelet concentrates have three standard characteristics: they act as scaffolds, they serve as a source of growth factors and cytokines, and they contain live cells. PRP has become extensively used in regenerative medicine for the successful treatment of a variety of clinical (non-)dermatological conditions like alopecies, acne scars, skin burns, skin ulcers, muscle, cartilage, and bone repair, and as an adjuvant in post-surgery wound healing, with obvious benefits in terms of functionality and aesthetic recovery of affected tissues/organs. These indications were well documented, and a large amount of evidence has already been published supporting the efficacy of this method. The primordial principle behind minimally invasive PRP treatments is the usage of the patient's own platelets. The benefits of the autologous transplantation of thrombocytes are significant, representing a fast and economic method that requires only basic equipment and training, and it is biocompatible, thus being a low risk for the patient (infection and immunological reactions can be virtually disregarded). Usually, the structural benefits of applying PRP are attributed to fibroblasts only, as they are considered the most numerous cell population within the interstitium. However, this apparent simplistic explanation is still eluding those different types of interstitial cells (distinct from fibroblasts) that are residing within stromal tissue, e.g., telocytes (TCs). Moreover, dermal TCs have an already documented potential in angiogenesis (extra-cutaneous, but also within skin), and their implication in skin recovery in a few dermatological conditions was attested and described ultrastructurally and immunophenotypically. Interestingly, PRP biochemically consists of a series of growth factors, cytokines, and other molecules, to which TCs have also proven to have a positive expression. Thus, it is attractive to hypothesize and to document any tissular collaboration between cutaneous administered PRP and local dermal TCs in skin recovery/repair/regeneration. Therefore, TCs could be perceived as the missing link necessary to provide a solid explanation of the good results achieved by administering PRP in skin-repairing processes.

Controlled human hookworm infection remodels plasmacytoid dendritic cells and regulatory T cells towards profiles seen in natural infections in endemic areas

Hookworm infection remains a significant public health concern, particularly in low- and middle-income countries, where mass drug administration has not stopped reinfection. Developing a vaccine is crucial to complement current control measures, which necessitates a thorough understanding of host immune responses. By leveraging controlled human infection models and high-dimensional immunophenotyping, here we investigated the immune remodeling following infection with 50 Necator americanus L3 hookworm larvae in four naïve volunteers over two years of follow-up and compared the profiles with naturally infected populations in endemic areas. Increased plasmacytoid dendritic cell frequency and diminished responsiveness to Toll-like receptor 7/8 ligand were observed in both controlled and natural infection settings. Despite the increased CD45RA+ regulatory T cell (Tregs) frequencies in both settings, markers of Tregs function, including inducible T-cell costimulatory (ICOS), tumor necrosis factor receptor 2 (TNFR2), and latency-associated peptide (LAP), as well as in vitro Tregs suppressive capacity were higher in natural infections. Taken together, this study provides unique insights into the immunological trajectories following a first-in-life hookworm infection compared to natural infections.

Design Strategy of Microneedle Systems for Skin Wound Healing: Based on the Structure of Tips and Therapeutic Methodologies

The skin, being the largest organ of the human body, is susceptible to damage resulting in wounds that are vulnerable to pathogenic attacks and fail to provide effective protection for internal tissues. Therefore, it is crucial to expedite wound healing. In recent years, microneedles have garnered significant attention as an innovative drug delivery system owing to their noninvasive and painless administration, simplified application process, precise control over drug release, and versatile loading capabilities. Consequently, they hold immense potential for the treatment of skin wound. This review presents a comprehensive design strategy for the microneedle system in promoting skin wound healing. First, the process of skin wound healing and the characteristics of specific wounds are elucidated. The design strategies for microneedles are subsequently presented and classified based on their structural and therapeutic methodologies. Finally, a succinct recapitulation of the previously discussed points and a prospective analysis are provided.

Oxidized Phospholipids Regulate Tenocyte Function via Induction of Amphiregulin in Dendritic Cells

Inflammation is a driving force of tendinopathy. The oxidation of phospholipids by free radicals is a consequence of inflammatory reactions and is an important indicator of tissue damage. Here, we have studied the impact of oxidized phospholipids (OxPAPC) on the function of human tenocytes. We observed that treatment with OxPAPC did not alter the morphology, growth and capacity to produce collagen in healthy or diseased tenocytes. However, since OxPAPC is a known modulator of the function of immune cells, we analyzed whether OxPAPC-treated immune cells might influence the fate of tenocytes. Co-culture of tenocytes with immature, monocyte-derived dendritic cells treated with OxPAPC (Ox-DCs) was found to enhance the proliferation of tenocytes, particularly those from diseased tendons. Using transcriptional profiling of Ox-DCs, we identified amphiregulin (AREG), a ligand for EGFR, as a possible mediator of this proliferation enhancing effect, which we could confirm using recombinant AREG. Of note, diseased tenocytes were found to express higher levels of EGFR compared to tenocytes isolated from healthy donors and show a stronger proliferative response upon co-culture with Ox-DCs, as well as AREG treatment. In summary, we identify an AREG-EGFR axis as a mediator of a DC-tenocyte crosstalk, leading to increased tenocyte proliferation and possibly tendon regeneration.

ROCK1 inhibition improves wound healing in diabetes via RIPK4/AMPK pathway

Refractory wounds are a severe complication of diabetes mellitus that often leads to amputation because of the lack of effective treatments and therapeutic targets. The pathogenesis of refractory wounds is complex, involving many types of cells. Rho-associated protein kinase-1 (ROCK1) phosphorylates a series of substrates that trigger downstream signaling pathways, affecting multiple cellular processes, including cell migration, communication, and proliferation. The present study investigated the role of ROCK1 in diabetic wound healing and molecular mechanisms. Our results showed that ROCK1 expression significantly increased in wound granulation tissues in diabetic patients, streptozotocin (STZ)-induced diabetic mice, and db/db diabetic mice. Wound healing and blood perfusion were dose-dependently improved by the ROCK1 inhibitor fasudil in diabetic mice. In endothelial cells, fasudil and ROCK1 siRNA significantly elevated the phosphorylation of adenosine monophosphate-activated protein kinase at Thr172 (pThr172-AMPKα), the activity of endothelial nitric oxide synthase (eNOS), and suppressed the levels of mitochondrial reactive oxygen species (mtROS) and nitrotyrosine formation. Experiments using integrated bioinformatics analysis and coimmunoprecipitation established that ROCK1 inhibited pThr172-AMPKα by binding to receptor-interacting serine/threonine kinase 4 (RIPK4). These results suggest that fasudil accelerated wound repair and improved angiogenesis at least partially through the ROCK1/RIPK4/AMPK pathway. Fasudil may be a potential treatment for refractory wounds in diabetic patients.

Exploiting temporal aspects of cancer immunotherapy

Many mechanisms underlying an effective immunotherapy-induced antitumour response are transient and critically time dependent. This is equally true for several immunological events in the tumour microenvironment induced by other cancer treatments. Immune checkpoint therapy (ICT) has proven to be very effective in the treatment of some cancers, but unfortunately, with many cancer types, most patients do not experience a benefit. To improve outcomes, a multitude of clinical trials are testing combinations of ICT with various other treatment modalities. Ideally, those combination treatments should take time-dependent immunological events into account. Recent studies have started to map the dynamic cellular and molecular changes that occur during treatment with ICT, in the tumour and systemically. Here, we overlay the dynamic ICT response with the therapeutic response following surgery, radiotherapy, chemotherapy and targeted therapies. We propose that by combining treatments in a time-conscious manner, we may optimally exploit the interactions between the individual therapies.

Combined analysis of single-cell sequencing and bulk transcriptome sequencing reveals new mechanisms for non-healing diabetic foot ulcers

Diabetic foot ulcers (DFUs) pose a significant challenge in diabetes care. Yet, a comprehensive understanding of the underlying biological disparities between healing and non-healing DFUs remains elusive. We conducted bioinformatics analysis of publicly available transcriptome sequencing data in an attempt to elucidate these differences. Our analysis encompassed differential analysis to unveil shifts in cell composition and gene expression profiles between non-healing and healing DFUs. Cell communication alterations were explored employing the Cellchat R package. Pseudotime analysis and cytoTRACE allowed us to dissect the heterogeneity within fibroblast subpopulations. Our findings unveiled disruptions in various cell types, localized low-grade inflammation, compromised systemic antigen processing and presentation, and extensive extracellular matrix signaling disarray in non-healing DFU patients. Some of these anomalies partially reverted in healing DFUs, particularly within the abnormal ECM-receptor signaling pathway. Furthermore, we distinguished distinct fibroblast subpopulations in non-healing and healing DFUs, each with unique biological functions. Healing-associated fibroblasts exhibited heightened extracellular matrix (ECM) remodeling and a robust wound healing response, while non-healing-associated fibroblasts showed signs of cellular senescence and complement activation, among other characteristics. This analysis offers profound insights into the wound healing microenvironment, identifies pivotal cell types for DFU healing promotion, and reveals potential therapeutic targets for DFU management.

Histone demethylase JARID1C/KDM5C regulates Th17 cells by increasing IL-6 expression in diabetic plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) are first responders to tissue injury, where they prime naive T cells. The role of pDCs in physiologic wound repair has been examined, but little is known about pDCs in diabetic wound tissue and their interactions with naive CD4+ T cells. Diabetic wounds are characterized by increased levels of inflammatory IL-17A cytokine, partly due to increased Th17 CD4+ cells. This increased IL-17A cytokine, in excess, impairs tissue repair. Here, using human tissue and murine wound healing models, we found that diabetic wound pDCs produced excess IL-6 and TGF-β and that these cytokines skewed naive CD4+ T cells toward a Th17 inflammatory phenotype following cutaneous injury. Further, we identified that increased IL-6 cytokine production by diabetic wound pDCs is regulated by a histone demethylase, Jumonji AT-rich interactive domain 1C histone demethylase (JARID1C). Decreased JARID1C increased IL-6 transcription in diabetic pDCs, and this process was regulated upstream by an IFN-I/TYK2/JAK1,3 signaling pathway. When inhibited in nondiabetic wound pDCs, JARID1C skewed naive CD4+ T cells toward a Th17 phenotype and increased IL-17A production. Together, this suggests that diabetic wound pDCs are epigenetically altered to increase IL-6 expression that then affects T cell phenotype. These findings identify a therapeutically manipulable pathway in diabetic wounds.

The interferon-rich skin environment regulates Langerhans cell ADAM17 to promote photosensitivity in lupus

The autoimmune disease lupus erythematosus (lupus) is characterized by photosensitivity, where even ambient ultraviolet radiation (UVR) exposure can lead to development of inflammatory skin lesions. We have previously shown that Langerhans cells (LCs) limit keratinocyte apoptosis and photosensitivity via a disintegrin and metalloprotease 17 (ADAM17)-mediated release of epidermal growth factor receptor (EGFR) ligands and that LC ADAM17 sheddase activity is reduced in lupus. Here, we sought to understand how the lupus skin environment contributes to LC ADAM17 dysfunction and, in the process, differentiate between effects on LC ADAM17 sheddase function, LC ADAM17 expression, and LC numbers. We show through transcriptomic analysis a shared IFN-rich environment in non-lesional skin across human lupus and three murine models: MRL/lpr, B6.Sle1yaa, and imiquimod (IMQ) mice. IFN-I inhibits LC ADAM17 sheddase activity in murine and human LCs, and IFNAR blockade in lupus model mice restores LC ADAM17 sheddase activity, all without consistent effects on LC ADAM17 protein expression or LC numbers. Anti-IFNAR-mediated LC ADAM17 sheddase function restoration is associated with reduced photosensitive responses that are dependent on EGFR signaling and LC ADAM17. Reactive oxygen species (ROS) is a known mediator of ADAM17 activity; we show that UVR-induced LC ROS production is reduced in lupus model mice, restored by anti-IFNAR, and is cytoplasmic in origin. Our findings suggest that IFN-I promotes photosensitivity at least in part by inhibiting UVR-induced LC ADAM17 sheddase function and raise the possibility that anifrolumab ameliorates lupus skin disease in part by restoring this function. This work provides insight into IFN-I-mediated disease mechanisms, LC regulation, and a potential mechanism of action for anifrolumab in lupus.

mRNA vaccines against infectious diseases and future direction

Vaccines are used for the control of infectious diseases of animals. Over other types of vaccinations like live attenuated or killed vaccines, mRNA-based vaccines have significant advantages. As only a small portion of the pathogen's genetic material is employed and the dose rate of mRNA-based vaccines is low, there is the least possibility that the pathogen will reverse itself. A carrier or vehicle that shields mRNA-based vaccines from the host's cellular RNases is necessary for their delivery. mRNA vaccines have been shown to be effective and to induce both a cell-mediated immune response and a humoral immune response in clinical trials against various infectious diseases (viral and parasitic) affecting the animals, including rabies, foot and mouth disease, toxoplasmosis, Zikavirus, leishmaniasis, and COVID-19. The current review aims to highlight the use of mRNA-based vaccines both in viral and parasitic diseases of animals.

Psoriasis and Psoriatic Arthritis-Associated Genes, Cytokines, and Human Leukocyte Antigens

In recent years, research has intensified in exploring the genetic basis of psoriasis (PsO) and psoriatic arthritis (PsA). Genome-wide association studies (GWASs), including tools like ImmunoChip, have significantly deepened our understanding of disease mechanisms by pinpointing risk-associated genetic loci. These efforts have elucidated biological pathways involved in PsO pathogenesis, particularly those related to the innate immune system, antigen presentation, and adaptive immune responses. Specific genetic loci, such as TRAF3IP2, REL, and FBXL19, have been identified as having a significant impact on disease development. Interestingly, different genetic variants at the same locus can predispose individuals to either PsO or PsA (e.g., IL23R and deletion of LCE3B and LCE3C), with some variants being uniquely linked to PsA (like HLA B27 on chromosome 6). This article aims to summarize known and new data on the genetics of PsO and PsA, their associated genes, and the involvement of the HLA system and cytokines.

Modulation of plasmacytoid dendritic cells response in inflammation and autoimmunity

The discovery of toll-like receptors (TLRs) and the subsequent recognition that endogenous nucleic acids (NAs) could serve as TLR ligands have led to essential insights into mechanisms of healthy immune responses as well as pathogenic mechanisms relevant to systemic autoimmune and inflammatory diseases. In systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis, NA-containing immune complexes serve as TLR ligands, with distinct implications depending on the additional immune stimuli available. Plasmacytoid dendritic cells (pDCs), the robust producers of type I interferon (IFN-I), are providing critical insights relevant to TLR-mediated healthy immune responses and tissue repair, as well as generation of inflammation, autoimmunity and fibrosis, processes central to the pathogenesis of many autoimmune diseases. In this review, we describe recent data characterizing the role of platelets and NA-binding chemokines in modulation of TLR signaling in pDCs, as well as implications for how the IFN-I products of pDCs contribute to the generation of inflammation and wound healing responses by monocyte/macrophages. Chemokine modulators of TLR-mediated B cell tolerance mechanisms and interactions between TLR signaling and metabolic pathways are also considered. The modulators of TLR signaling and their contribution to the pathogenesis of systemic autoimmune diseases suggest new opportunities for identification of novel therapeutic targets.

Tissue adaptation of CD4 T lymphocytes in homeostasis and cancer

The immune system is traditionally classified as a defense system that can discriminate between self and non-self or dangerous and non-dangerous situations, unleashing a tolerogenic reaction or immune response. These activities are mainly coordinated by the interaction between innate and adaptive cells that act together to eliminate harmful stimuli and keep tissue healthy. However, healthy tissue is not always the end point of an immune response. Much evidence has been accumulated over the years, showing that the immune system has complex, diversified, and integrated functions that converge to maintaining tissue homeostasis, even in the absence of aggression, interacting with the tissue cells and allowing the functional maintenance of that tissue. One of the main cells known for their function in helping the immune response through the production of cytokines is CD4+ T lymphocytes. The cytokines produced by the different subtypes act not only on immune cells but also on tissue cells. Considering that tissues have specific mediators in their architecture, it is plausible that the presence and frequency of CD4+ T lymphocytes of specific subtypes (Th1, Th2, Th17, and others) maintain tissue homeostasis. In situations where homeostasis is disrupted, such as infections, allergies, inflammatory processes, and cancer, local CD4+ T lymphocytes respond to this disruption and, as in the healthy tissue, towards the equilibrium of tissue dynamics. CD4+ T lymphocytes can be manipulated by tumor cells to promote tumor development and metastasis, making them a prognostic factor in various types of cancer. Therefore, understanding the function of tissue-specific CD4+ T lymphocytes is essential in developing new strategies for treating tissue-specific diseases, as occurs in cancer. In this context, this article reviews the evidence for this hypothesis regarding the phenotypes and functions of CD4+ T lymphocytes and compares their contribution to maintaining tissue homeostasis in different organs in a steady state and during tumor progression.

Circulating immunome fingerprint in eosinophilic esophagitis is associated with clinical response to proton pump inhibitor treatment

Objectives

The aim of the study was to characterize the circulating immunome of patients with EoE before and after proton pump inhibitor (PPI) treatment in order to identify potential non-invasive biomarkers of treatment response.

Methods

PBMCs from 19 healthy controls and 24 EoE patients were studied using a 39-plex spectral cytometry panel. The plasmacytoid dendritic cell (pDC) population was differentially characterized by spectral cytometry analysis and immunofluorescence assays in esophageal biopsies from 7 healthy controls and 13 EoE patients.

Results

Interestingly, EoE patients at baseline had lower levels of circulating pDC compared with controls. Before treatment, patients with EoE who responded to PPI therapy had higher levels of circulating pDC and classical monocytes, compared with non-responders. Moreover, following PPI therapy pDC levels were increased in all EoE patients, while normal levels were only restored in PPI-responding patients. Finally, circulating pDC levels inversely correlated with peak eosinophil count and pDC count in esophageal biopsies. The number of tissue pDCs significantly increased during active EoE, being even higher in non-responder patients when compared to responder patients pre-PPI. pDC levels decreased after PPI intake, being further restored almost to control levels in responder patients post-PPI.

Conclusions

We hereby describe a unique immune fingerprint of EoE patients at diagnosis. Moreover, circulating pDC may be also used as a novel non-invasive biomarker to predict subsequent response to PPI treatment.

Role of the Skin Immune System in Wound Healing

Wound healing is a dynamic and complex process, characterized by the coordinated activities of multiple cell types, each with distinct roles in the stages of hemostasis, inflammation, proliferation, and remodeling. The cells of the immune system not only act as sentinels to monitor the skin and promote homeostasis, but they also play an important role in the process of skin wound repair. Skin-resident and recruited immune cells release cytokines and growth factors that promote the amplification of the inflammatory process. They also work with non-immune cells to remove invading pathogens and debris, as well as guide the regeneration of damaged host tissues. Dysregulation of the immune system at any stage of the process may lead to a prolongation of the inflammatory phase and the development of a pathological condition, such as a chronic wound. The present review aims to summarize the roles of different immune cells, with special emphasis on the different stages of the wound healing process.

γδ T Cells Mediate a Requisite Portion of a Wound Healing Response Triggered by Cutaneous Poxvirus Infection

Infection at barrier sites, e.g., skin, activates local immune defenses that limit pathogen spread, while preserving tissue integrity. Phenotypically distinct γδ T cell populations reside in skin, where they shape immunity to cutaneous infection prior to onset of an adaptive immune response by conventional αβ CD4+ (TCD4+) and CD8+ (TCD8+) T cells. To examine the mechanisms used by γδ T cells to control cutaneous virus replication and tissue pathology, we examined γδ T cells after infection with vaccinia virus (VACV). Resident γδ T cells expanded and combined with recruited γδ T cells to control pathology after VACV infection. However, γδ T cells did not play a role in control of local virus replication or blockade of systemic virus spread. We identified a unique wound healing signature that has features common to, but also features that antagonize, the sterile cutaneous wound healing response. Tissue repair generally occurs after clearance of a pathogen, but viral wound healing started prior to the peak of virus replication in the skin. γδ T cells contributed to wound healing through induction of multiple cytokines/growth factors required for efficient wound closure. Therefore, γδ T cells modulate the wound healing response following cutaneous virus infection, maintaining skin barrier function to prevent secondary bacterial infection.

Increased LL37 in psoriasis and other inflammatory disorders promotes LDL uptake and atherosclerosis

Patients with chronic inflammatory disorders such as psoriasis have an increased risk of cardiovascular disease and elevated levels of LL37, a cathelicidin host defense peptide that has both antimicrobial and proinflammatory properties. To explore whether LL37 could contribute to the risk of heart disease, we examined its effects on lipoprotein metabolism and show that LL37 enhanced LDL uptake in macrophages through the LDL receptor (LDLR), scavenger receptor class B member 1 (SR-B1), and CD36. This interaction led to increased cytosolic cholesterol in macrophages and changes in expression of lipid metabolism genes consistent with increased cholesterol uptake. Structure-function analysis and synchrotron small-angle x-ray scattering showed structural determinants of the LL37-LDL complex that underlie its ability to bind its receptors and promote uptake. This function of LDL uptake is unique to cathelicidins from humans and some primates and was not observed with cathelicidins from mice or rabbits. Notably, Apoe-/- mice expressing LL37 developed larger atheroma plaques than did control mice, and a positive correlation between plasma LL37 and oxidized phospholipid on apolipoprotein B (OxPL-apoB) levels was observed in individuals with cardiovascular disease. These findings provide evidence that LDL uptake can be increased via interaction with LL37 and may explain the increased risk of cardiovascular disease associated with chronic inflammatory disorders.

Triggers for the onset and recurrence of psoriasis: a review and update

Psoriasis is an immune-mediated inflammatory skin disease, involving a complex interplay between genetic and environmental factors. Previous studies have demonstrated that genetic factors play a major role in the pathogenesis of psoriasis. However, non-genetic factors are also necessary to trigger the onset and recurrence of psoriasis in genetically predisposed individuals, which include infections, microbiota dysbiosis of the skin and gut, dysregulated lipid metabolism, dysregulated sex hormones, and mental illness. Psoriasis can also be induced by other environmental triggers, such as skin trauma, unhealthy lifestyles, and medications. Understanding how these triggers play a role in the onset and recurrence of psoriasis provides insights into psoriasis pathogenesis, as well as better clinical administration. In this review, we summarize the triggers for the onset and recurrence of psoriasis and update the current evidence on the underlying mechanism of how these factors elicit the disease. Video Abstract.

Regulatory T cells in skin mediate immune privilege of the hair follicle stem cell niche

Immune tolerance is maintained in lymphoid organs (LOs). Despite the presence of complex immune cell networks in non-LOs, it is unknown whether self-tolerance is maintained in these tissues. We developed a technique to restrict genetic recombination to regulatory T cells (Tregs) only in skin. Selective depletion of skin Tregs resulted in T cell-mediated inflammation of hair follicles (HFs). Suppression did not rely on CTLA-4, but instead on high-affinity interleukin-2 (IL-2) receptor expression by skin Tregs, functioning exclusively in a cell-extrinsic manner. In a novel model of HF stem cell (HFSC)-driven autoimmunity, we reveal that skin Tregs immunologically protect the HFSC niche. Finally, we used spatial transcriptomics to identify aberrant IL-2 signaling at stromal-HF interfaces in a rare form of human alopecia characterized by HFSC destruction and alopecia areata. Collectively, these results reveal the fundamental biology of Tregs in skin uncoupled from the systemic pool and elucidate a mechanism of self-tolerance.

Paradoxical psoriasis: The flip side of idiopathic psoriasis or an autocephalous reversible drug reaction?

Psoriasis is a common, chronic skin disease that results mainly from the complex interplay between T cells, dendritic cells, and inflammatory cytokines including TNF-α, IL-17, IL-12, and IL-23. Successful therapy with anti-cytokine antibodies has proved the importance of these key cytokines, especially TNF-α. During the anti-TNF-α treatment of classical idiopathic psoriasis, a small portion of patients develop new psoriasiform lesions. This contradictory phenomenon was named paradoxical psoriasis which resembles idiopathic psoriasis clinically but presents overlapped histological patterns and distinct immunological processes. In this review, we discuss the differences between idiopathic psoriasis and paradoxical psoriasis with an emphasis on their innate immunity, as it is predominant in paradoxical psoriasis which exhibits type I IFN-mediated immunity without the activation of autoreactive T cells and memory T cells. We also put up an instructive algorithm for the management of paradoxical psoriasis. The decision on drug discontinuation or switching of biologics should be made based on the condition of underlying diseases and the severity of lesions.

Anifrolumab for Moderate and Severe Muco-Cutaneous Lupus Erythematosus: A Monocentric Experience and Review of the Current Literature

Refractory cutaneous manifestations constitute a significant unmet need in patients with cutaneous lupus (CLE), even in the setting of systemic lupus erythematosus (SLE) with otherwise good control of inflammatory manifestations. Anifrolumab, an anti-interferon I receptor monoclonal antibody has recently been approved for serologically positive SLE with or without CLE, but real-life efficacy and safety data are currently limited. In addition, relatively limited evidence exists about the spectrum of cutaneous manifestations potentially benefitting from anifrolumab treatment and about the optimal clinimetrics to monitor treatment efficacy. While summarising current evidence on the topic in the literature, we report on four patients with SLE and refractory CLE who were successfully treated with anifrolumab. We also describe the potential usefulness and complementarity of the cutaneous lupus activity investigator's global assessment (CLA-IGA) in assessing cutaneous activity in patients treated with anifrolumab.

The IFIH1/MDA5 rs1990760 Gene Variant (946Thr) Differentiates Early- vs. Late-Onset Skin Disease and Increases the Risk of Arthritis in a Spanish Cohort of Psoriasis

The melanoma differentiation-associated protein 5 (MDA5; encoded by the IFIH1 gene) mediates the activation of the interferon pathway in response to a viral infection. This protein is also upregulated in autoimmune diseases and psoriasis skin lesions. IFIH1 gene variants that increase MDA5 activity have been associated with an increased risk for immune-mediated diseases, including psoriasis. Our aim is to determine the association between three IFIH1 variants (rs35337543 G/C, intron8 + 1; rs35744605 C/A, Glu627Stop; and rs1990760 C/T, Ala946Thr) and the main clinical findings in a cohort of Spanish patients with psoriasis (N = 572; 77% early-onset). Early-onset psoriasis patients (EOPs) had a significantly higher frequency of severe disease and the Cw6*0602 allele. Carriers of rs1990760 T (946Thr) were more common in the EOPs (p < 0.001), and the effect was more pronounced among Cw6*0602-negatives. This variant was also associated with an increased risk of psoriatic arthritis (PsA) independent from other factors (OR = 1.62, 95%CI = 1.11-2.37). The rs3533754 and rs35744605 polymorphisms did not show significant differences between the two onset age or PsA groups. Compared to the controls, the 946Thr variant was more common in the EOPs (nonsignificant difference) and significantly less common in patients aged >40 years (p = 0.005). In conclusion, the common IFIH1 rs1990760 T allele was significantly more frequent in early-onset compared to late-onset patients. This variant was also an independent risk factor for PsA in our cohort. Our study reinforces the widely reported role of the IFIH1 gene variants on psoriatic disease.

TLR7 promotes skin inflammation via activating NFκB-mTORC1 axis in rosacea

Rosacea is a chronic inflammatory skin disease originated from damaged skin barrier and innate/adaptive immune dysregulation. Toll-like receptors (TLRs) sense injured skin and initiate downstream inflammatory and immune responses, whose role in rosacea is not fully understood. Here, via RNA-sequencing analysis, we found that the TLR signaling pathway is the top-ranked signaling pathway enriched in rosacea skin lesions, in which TLR7 is highlighted and positively correlated with the inflammation severity of disease. In LL37-induced rosacea-like mouse models, silencing TLR7 prevented the development of rosacea-like skin inflammation. Specifically, we demonstrated that overexpressing TLR7 in keratinocytes stimulates rapamycin-sensitive mTOR complex 1 (mTORC1) pathway via NFκB signaling. Ultimately, TLR7/NFκ B/mTORC1 axis promotes the production of cytokines and chemokines, leading to the migration of CD4+T cells, which are infiltrated in the lesional skin of rosacea. Our report reveals the crucial role of TLR7 in rosacea pathogenesis and indicatesa promising candidate for rosacea treatments.

DOCK8 is essential for neutrophil mediated clearance of cutaneous S. aureus infection

DOCK8 deficient patients are susceptible to skin infection with Staphylococcus aureus which is normally cleared by neutrophils. We examined the mechanism of this susceptibility in mice. Dock8-/- mice had delayed clearance of S. aureus from skin mechanically injured by tape stripping. The numbers and viability of neutrophils in infected but not in uninfected, tape stripped skin were significantly reduced in Dock8-/- mice compared to WT controls. This is despite comparable numbers of circulating neutrophils, and normal to elevated cutaneous expression of Il17a and IL-17A inducible neutrophil attracting chemokines Cxcl1, Cxcl2 and Cxcl3. DOCK8 deficient neutrophils were significantly more susceptible to cell death upon in vitro exposure to S. aureus and exhibited reduced phagocytosis of S. aureus bioparticles but had a normal respiratory burst. Impaired neutrophil survival in infected skin and defective neutrophil phagocytosis likely underlie the susceptibility to cutaneous S. aureus infection in DOCK8 deficiency.

Psoriasis: Striving for Potential Biomarkers

Psoriasis is a chronic disease that is caused by multiple factors and is identified by itchiness, unpleasant, red, or white scaly patches on the skin, particularly on regularly chafed body regions such as the lateral areas of the limbs. Reports suggest that globally around 2%-3% of the population suffers from psoriasis. In this review, we have discussed the clinical classification of psoriasis and also the ideal characteristics of the biomarkers. An overview regarding the discovery of the biomarker and method for validating the study has been discussed. A growing body of research suggests a link to certain other systemic symptoms such as cardiovascular disorder, metabolic syndrome, and few other comorbidities such as hypertension and nonalcoholic fatty liver disease. Natural killer (NK) cells are lymphocyte cells that concentrate on the destruction of virally infected and malignant cells; these tend to produce a wide range of inflammatory cytokines, some of which are associated with the etiology of psoriasis. Detailed information on the molecular pathogenesis of psoriasis in which interleukin (IL)-17, IL-23, tumor necrosis factor-α (TNF-α), and CCL20 play a very significant role in the development of psoriasis. In this review, we have discussed an overview of the recent state of the biomarkers available for the diagnosis and treatment of psoriasis by emphasizing on the available biomarkers such as epigenomic, transcriptomic, glycomic, and metabolomic. The most recent advancements in molecular-targeted therapy utilizing biologics and oral systemic therapy (methotrexate, apremilast) enable to adequately treat the most serious psoriatic symptoms and also the studies have validated the efficacy of biologic therapy such as TNF-α antagonist (infliximab, adalimumab), IL-23 antagonist (guselkumab, risankizumab), and IL-17 antagonist (secukinumab, ixekizumab). Finally, an overview about the technological opportunities as well as various challenges has been discussed.

Mechanisms of neutrophil extracellular trap in chronic inflammation of endothelium in atherosclerosis

Cardiovascular diseases are a primary cause of morbidity and mortality around the world. In addition, atherosclerosis (AS)-caused cardiovascular disease is the primary cause of death in human diseases, and almost two billion people suffer from carotid AS worldwide. AS is caused by chronic inflammation of the arterial vessel and is initiated by dysfunction of vascular endothelial cells. Neutrophils protect against pathogen invasion because they function as a component of the innate immune system. However, the contribution of neutrophils to cardiovascular disease has not yet been clarified. Neutrophil extracellular traps (NETs) represent an immune defense mechanism that is different from direct pathogen phagocytosis. NETs are extracellular web-like structures activated by neutrophils, and they play important roles in promoting endothelial inflammation via direct or indirect pathways. NETs consist of DNA, histones, myeloperoxidase, matrix metalloproteinases, proteinase 3, etc. Most of the components of NETs have no direct toxic effect on endothelial cells, such as DNA, but they can damage endothelial cells indirectly. In addition, NETs play a critical role in the process of AS; therefore, it is important to clarify the mechanisms of NETs in AS because NETs are a new potential therapeutic target AS. This review summarizes the possible mechanisms of NETs in AS.

Ultraviolet radiation shapes dendritic cell leukaemia transformation in the skin

Tumours most often arise from progression of precursor clones within a single anatomical niche. In the bone marrow, clonal progenitors can undergo malignant transformation to acute leukaemia, or differentiate into immune cells that contribute to disease pathology in peripheral tissues1-4. Outside the marrow, these clones are potentially exposed to a variety of tissue-specific mutational processes, although the consequences of this are unclear. Here we investigate the development of blastic plasmacytoid dendritic cell neoplasm (BPDCN)-an unusual form of acute leukaemia that often presents with malignant cells isolated to the skin5. Using tumour phylogenomics and single-cell transcriptomics with genotyping, we find that BPDCN arises from clonal (premalignant) haematopoietic precursors in the bone marrow. We observe that BPDCN skin tumours first develop at sun-exposed anatomical sites and are distinguished by clonally expanded mutations induced by ultraviolet (UV) radiation. A reconstruction of tumour phylogenies reveals that UV damage can precede the acquisition of alterations associated with malignant transformation, implicating sun exposure of plasmacytoid dendritic cells or committed precursors during BPDCN pathogenesis. Functionally, we find that loss-of-function mutations in Tet2, the most common premalignant alteration in BPDCN, confer resistance to UV-induced cell death in plasmacytoid, but not conventional, dendritic cells, suggesting a context-dependent tumour-suppressive role for TET2. These findings demonstrate how tissue-specific environmental exposures at distant anatomical sites can shape the evolution of premalignant clones to disseminated cancer.

Chemo-mechanical diffusion waves explain collective dynamics of immune cell podosomes

Immune cells, such as macrophages and dendritic cells, can utilize podosomes, mechanosensitive actin-rich protrusions, to generate forces, migrate, and patrol for foreign antigens. Individual podosomes probe their microenvironment through periodic protrusion and retraction cycles (height oscillations), while oscillations of multiple podosomes in a cluster are coordinated in a wave-like fashion. However, the mechanisms governing both the individual oscillations and the collective wave-like dynamics remain unclear. Here, by integrating actin polymerization, myosin contractility, actin diffusion, and mechanosensitive signaling, we develop a chemo-mechanical model for podosome dynamics in clusters. Our model reveals that podosomes show oscillatory growth when actin polymerization-driven protrusion and signaling-associated myosin contraction occur at similar rates, while the diffusion of actin monomers drives wave-like coordination of podosome oscillations. Our theoretical predictions are validated by different pharmacological treatments and the impact of microenvironment stiffness on chemo-mechanical waves. Our proposed framework can shed light on the role of podosomes in immune cell mechanosensing within the context of wound healing and cancer immunotherapy.

Histone deacetylase inhibitors as a potential new treatment for psoriatic disease and other inflammatory conditions

Collectively known as psoriatic disease, psoriasis and psoriatic arthritis (PsA) are immune-mediated inflammatory diseases in which patients present with cutaneous and musculoskeletal inflammation. Affecting roughly 2-3% of the world's total population, there remains unmet therapeutic needs in both psoriasis and PsA despite the availability of current immunomodulatory treatments. As a result, patients with psoriatic disease often experience reduced quality of life. Recently, a class of small molecules, commonly investigated as anti-cancer agents, called histone deacetylase (HDAC) inhibitors, have been proposed as a new promising anti-inflammatory treatment for immune- and inflammatory-related diseases. In inflammatory diseases, current evidence is derived from studies on diseases like rheumatoid arthritis (RA) and systematic lupus erythematosus (SLE), and while there are some reports studying psoriasis, data on PsA patients are not yet available. In this review, we provide a brief overview of psoriatic disease, psoriasis, and PsA, as well as HDACs, and discuss the rationale behind the potential use of HDAC inhibitors in the management of persistent inflammation to suggest its possible use in psoriatic disease.

Type I IFNs link skin-associated dysbiotic commensal bacteria to pathogenic inflammation and angiogenesis in rosacea

Rosacea is a common chronic inflammatory skin disease with a fluctuating course of excessive inflammation and apparent neovascularization. Microbial dysbiosis with a high density of Bacillus oleronius and increased activity of kallikrein 5, which cleaves cathelicidin antimicrobial peptide, are key pathogenic triggers in rosacea. However, how these events are linked to the disease remains unknown. Here, we show that type I IFNs produced by plasmacytoid DCs represent the pivotal link between dysbiosis, the aberrant immune response, and neovascularization. Compared with other commensal bacteria, B. oleronius is highly susceptible and preferentially killed by cathelicidin antimicrobial peptides, leading to enhanced generation of complexes with bacterial DNA. These bacterial DNA complexes but not DNA complexes derived from host cells are required for cathelicidin-induced activation of plasmacytoid DCs and type I IFN production. Moreover, kallikrein 5 cleaves cathelicidin into peptides with heightened DNA binding and type I IFN-inducing capacities. In turn, excessive type I IFN expression drives neoangiogenesis via IL-22 induction and upregulation of the IL-22 receptor on endothelial cells. These findings unravel a potentially novel pathomechanism that directly links hallmarks of rosacea to the killing of dysbiotic commensal bacteria with induction of a pathogenic type I IFN-driven and IL-22-mediated angiogenesis.

Acute Inflammation in Tissue Healing

There are well-established links between acute inflammation and successful tissue repair across evolution. Innate immune reactions contribute significantly to pathogen clearance and activation of subsequent reparative events. A network of molecular and cellular regulators supports antimicrobial and tissue repair functions throughout the healing process. A delicate balance must be achieved between protection and the potential for collateral tissue damage associated with overt inflammation. In this review, we summarize the contributions of key cellular and molecular components to the acute inflammatory process and the effective and timely transition toward activation of tissue repair mechanisms. We further discuss how the disruption of inflammatory responses ultimately results in chronic non-healing injuries.

Exploration of and insights into advanced topical nanocarrier systems for the treatment of psoriasis

Psoriasis is a chronic inflammatory skin disease with an underlying autoimmune pathogenesis that has brought great distress to patients. Current treatment options include topical therapy, systemic therapy, and phototherapy. By disrupting the stratum corneum, nanocarriers have unique advantages in allowing drug carriers to be tailored to achieve targeted drug delivery, improve efficacy, and minimize adverse effects. Furthermore, despite their limited success in market translatability, nanocarriers have been extensively studied for psoriasis, owing to their excellent preclinical results. As topical formulations are the first line of treatment, utilize the safest route, and facilitate a targeted approach, this study, we specifically describes the management of psoriasis using topical agents in conjunction with novel drug delivery systems. The characteristics, advantages, weaknesses, and mechanisms of individual nanocarriers, when applied as topical anti-psoriatic agents, were reviewed to distinguish each nanocarrier.

Gastric alarmin release: A warning signal in the development of gastric mucosal diseases

Alarmins exist outside cells and are early warning signals to the immune system; as such, alarmin receptors are widely distributed on various immune cells. Alarmins, proinflammatory molecular patterns associated with tissue damage, are usually released into the extracellular space, where they induce immune responses and participate in the damage and repair processes of mucosal diseases.In the stomach, gastric alarmin release has been shown to be involved in gastric mucosal inflammation, antibacterial defense, adaptive immunity, and wound healing; moreover, this release causes damage and results in the development of gastric mucosal diseases, including various types of gastritis, ulcers, and gastric cancer. Therefore, it is necessary to understand the role of alarmins in gastric mucosal diseases. This review focuses on the contribution of alarmins, including IL33, HMGB1, defensins and cathelicidins, to the gastric mucosal barrier and their role in gastric mucosal diseases. Here, we offer a new perspective on the prevention and treatment of gastric mucosal diseases.

How cell migration helps immune sentinels

The immune system relies on the migratory capacity of its cellular components, which must be mobile in order to defend the host from invading micro-organisms or malignant cells. This applies in particular to immune sentinels from the myeloid lineage, i.e. macrophages and dendritic cells. Cell migration is already at work during mammalian early development, when myeloid cell precursors migrate from the yolk sac, an extra embryonic structure, to colonize tissues and form the pool of tissue-resident macrophages. Later, this is accompanied by a migration wave of precursors and monocytes from the bone marrow to secondary lymphoid organs and the peripheral tissues. They differentiate into DCs and monocyte-derived macrophages. During adult life, cell migration endows immune cells with the ability to patrol their environment as well as to circulate between peripheral tissues and lymphoid organs. Hence migration of immune cells is key to building an efficient defense system for an organism. In this review, we will describe how cell migratory capacity regulates the various stages in the life of myeloid cells from development to tissue patrolling, and migration to lymph nodes. We will focus on the role of the actin cytoskeletal machinery and its regulators, and how it contributes to the establishment and function of the immune system.

The role of mast cells in cellular modifications evoked by Exendin-4 in treated wounds: a preclinical study

OBJECTIVE

To assess the response of cellular infiltration in wounds treated with Exendin-4.

METHOD

In this study, 16 mice were used. On each mouse, two wounds were produced, one above the other, in order to study the effects of the various treatments carried out. The wounds then received an intradermal injection of either saline (20μl; Group 1) or Exendin-4 (Exe4, 62ng; Group 2) in the upper and lower wounds, respectively. The mice were euthanised in order to collect the wounds at time of abrasion (T0), at 48 hours (T1), 96 hours (T2) and 144 hours (T3). The expression of the glucagon-like peptide-1 receptor (GLP-1R) was evaluated by Western blot in wound lysates. Histological and histochemistry methods were applied in cryosections.

RESULTS

In T2 and T3 treated wounds, the mast cells degranulation index increased while GLP-1R expression, tumour necrosis factor (TNF)-α, or heat shock protein (HSP)47 antigens were detected in their cytoplasm. These cells interacted with dendritic cells, vessels or granulocytes. The density of dendritic cells increased progressively, and intercellular connections were found between these cells and vessels. Among the dendritic cells at T2, only M2 macrophages increased. However, M1 cells expressed transforming growth factor (TGF)-β and both interacted with either fibroblasts or with vessels. The number of plasmacytoid dendritic cells increased and established close contacts with regulatory T cells.

CONCLUSION

We propose that after treatment with Exe4, early activation of mast cells is critical in wound healing acceleration. This is crucial in understanding the potential effect of this drug for viable clinical therapies.

DECLARATION OF INTEREST

No potential conflict of interest was reported by the authors.

Topical VX-509 attenuates psoriatic inflammation through the STAT3/FABP5 pathway in keratinocytes

BACKGROUND

Psoriasis is a chronic inflammatory disease, with lesions mainly manifesting as scaly erythematous plaques. The mild or moderate of psoriasis is the main type of patients in hospital, and topical application remains the preferred treatment option for psoriasis therapy, therefore, the development of novel topical agents has an essential role in psoriasis therapy.

OBJECTIVE

To identify potential drugs for psoriasis topical treatment.

METHODS

We performed drug screening by Imiquimod (IMQ)-induced psoriatic like inflammation in mouse model, followed mouse epidermis by RNA-seq to find the key molecules affecting the drug. The qRT-PCR, WB were performed to test mRNA and protein expression, and Chip assay had been conducted to examine Stat3 bound to promoter of FABP5.

RESULTS

In this study, we identified VX-509, which topical application significantly attenuated IMQ-induced psoriatic like inflammation in mouse model. And then, we verified Epidermal Fatty acid binding protein (E-FABP/FABP5) was significantly decreased in VX-509 treated mouse epidermis by RNA-seq. FABP5 is a key molecule in lipid metabolism, administration of FABP5 inhibitor or knock down of FABP5 expression remarkably abrogated psoriatic inflammation as well as lipid metabolism. Mechanistically, our finding showed that VX-509 blocked IL-22 induced signaling pathway, particular in activation of Stat3. Furthermore, we identified Stat3 is a transcriptional factor associated with FABP5 promoters and VX-509 treatment remarkably attenuated IL-22-induced FABP5 expression through Stat3 in KCs.

CONCLUSIONS

This study demonstrated administration of VX-509 is a potential promising topical drug for treatment of psoriasis, FABP5 is a critical targeted molecule in psoriasis therapy.

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.

Healing Mechanisms in Cutaneous Wounds: Tipping the Balance

Acute and chronic cutaneous wounds pose a significant health and economic burden. Cutaneous wound healing is a complex process that occurs in four distinct, yet overlapping, highly coordinated stages: hemostasis, inflammation, proliferation, and remodeling. Postnatal wound healing is reparative, which can lead to the formation of scar tissue. Regenerative wound healing occurs during fetal development and in restricted postnatal tissues. This process can restore the wound to an uninjured state by producing new skin cells from stem cell reservoirs, resulting in healing with minimal or no scarring. Focusing on the pathophysiology of acute burn wounds, this review highlights reparative and regenerative healing mechanisms (including the role of cells, signaling molecules, and the extracellular matrix) and discusses how components of regenerative healing are being used to drive the development of novel approaches and therapeutics aimed at improving clinical outcomes. Important components of regenerative healing, such as stem cells, growth factors, and decellularized dermal matrices, are all being evaluated to recapitulate more closely the natural regenerative healing process.