Psoriatic scales: a promising source for the isolation of human skin-derived antimicrobial proteins

Breakthrough Opportunities of Nanotheranostics in Psoriasis: From Pathogenesis to Management Strategy

BACKGROUND

In this paper, we have discussed recent advances in our understanding of the aetiology of psoriasis, particularly as they relate to aryl hydrocarbon receptors in DCs, Langerhans cells, macrophages, signal transducer and activator of transcription 3 pathways, and dermal vascular endothelial cells. Here, we have shown that the ability to target specific cellular and molecular components of psoriasis pathogenesis with nanoscale precision using phosphodiesterase 4 inhibitors represents a transformative opportunity to address the complex nature of this dermatological condition.

OBJECTIVE

In this review, we have examined the molecular mechanisms behind the pathogenic features of psoriasis and new treatments being tested in clinical settings. There is research being done on new treatments created in the last ten years. This field highlights the advantages of nanotechnological technologies as cutting-edge candidates for drug delivery systems in psoriasis and other inflammatory chronic skin disorders. Future Developments: Nanotechnology-based treatments currently under study show good efficacy and low side effect profiles. However, long-term prospective trials are required to demonstrate long-term safety and effectiveness. Phosphodiesterase inhibitors, Janus kinase inhibitors, nonsteroidal anti-inflammatory drugs, combinations of vitamin D3 derivatives and corticosteroids, and coal tar formulations are some of the newer topical treatments for psoriasis.

CONCLUSION

The psoriasis treatment continues to involve conventional medications (i.e., medicines that are generally acknowledged as either normal therapy or outdated remedies), whether used topically or orally. Nonetheless, we are starting to see initiatives to create pharmaceuticals and biosimilars with better therapeutic results, fewer side effects, and greater efficacy.

Comparative Whole Metagenome Analysis in Lesional and Nonlesional Scalp Areas of Patients with Psoriasis Capitis and Healthy Individuals

Psoriasis is an immune-mediated inflammatory disorder, where the majority of the patients suffer from psoriasis capitis or scalp psoriasis. Current therapeutics remain ineffective to treat scalp lesions. In this study, we present a whole-metagenome characterization of the scalp microbiome in psoriasis capitis. We investigated how changes in the homeostatic cutaneous microbiome correlate with the condition and identified metagenomic biomarkers (taxonomic, functional, virulence factors, antimicrobial resistance genes) that could partly explain its emergence. Within this study, 83 top and back scalp samples from healthy individuals and 64 lesional and nonlesional scalp samples from subjects with untreated psoriasis capitis were analyzed. Using qPCR targeting the 16S and 18S ribosomal RNA genes, we found a significant decrease in microbial load within scalp regions affected by psoriasis compared with that in their nonlesional counterparts. Metagenomic analysis revealed that psoriatic lesions displayed significant lower Cutibacterium species (including C. modestum, C. namnetense, C. granulosum, C. porci), along with an elevation in Staphylococcus aureus. A heightened relative presence of efflux pump protein-encoding genes was detected, suggesting potential antimicrobial resistance mechanisms. These mechanisms are known to specifically target human antimicrobial peptides (including cathelicidin LL-37), which are frequently encountered within psoriasis lesions. These shifts in microbial community dynamics may contribute to psoriasis disease pathogenesis.

Inhibition of RNase 7 by RNase inhibitor promotes inflammation and Staphylococcus aureus growth: Implications for atopic dermatitis

BACKGROUND

The antimicrobial ribonuclease RNase 7 is abundantly expressed in the epidermis of lesional skin of atopic dermatitis (AD). Host RNase inhibitor (RI) binds to RNase 7 and blocks its ribonuclease activity. This study aimed to evaluate the impact of RNase 7-RI interactions on AD.

METHODS

Cultured human primary keratinocytes, with siRNA-mediated downregulation of RNase 7 and RI, were stimulated with the synthetic RNA polyinosinic-polycytidylic acid (poly I:C). Induction of proinflammatory mediators was analyzed by real-time PCR and ELISA. RI expression in AD non-lesional and lesional skin biopsies and healthy controls was analyzed by real-time PCR and immunostaining. RI protein release in vivo on the AD skin surface was determined by western blot. Antimicrobial and ribonuclease assays were used to investigate the functional role of RI.

RESULTS

RNase 7 inhibited the RNA-induced expression of proinflammatory mediators in keratinocytes. Accordingly, downregulation of RNase 7 in keratinocytes enhanced RNA-mediated induction of proinflammatory mediators, whereas downregulation of RI had the opposite effect. RI was released by damaged keratinocytes and epidermis. In vivo expression and release of RI on the skin surface were enhanced in lesional AD skin. Rinsing solution from the surface of lesional AD skin blocked the ribonuclease activity of RNase 7. The anti-Staphylococcus aureus activity of RNase 7 was abrogated by RI.

CONCLUSIONS

Our data suggest a novel role of RI as a trigger factor of inflammation in AD by blocking the ribonuclease and antimicrobial activity of RNase 7, thereby enhancing RNA-mediated inflammation and S. aureus growth.

The Role of Alarmins in the Pathogenesis of Rheumatoid Arthritis, Osteoarthritis, and Psoriasis

Alarmins are immune-activating factors released after cellular injury or death. By secreting alarmins, cells can interact with immune cells and induce a variety of inflammatory responses. The broad family of alarmins involves several members, such as high-mobility group box 1, S100 proteins, interleukin-33, and heat shock proteins, among others. Studies have found that the concentrations and expression profiles of alarmins are altered in immune-mediated diseases. Furthermore, they are involved in the pathogenesis of inflammatory conditions. The aim of this narrative review is to present the current evidence on the role of alarmins in rheumatoid arthritis, osteoarthritis, and psoriasis. We discuss their potential involvement in mechanisms underlying the progression of these diseases and whether they could become therapeutic targets. Moreover, we summarize the impact of pharmacological agents used in the treatment of these diseases on the expression of alarmins.

Exploring therapeutic avenues: mesenchymal stem/stromal cells and exosomes in confronting enigmatic biofilm-producing fungi

Fungal infections concomitant with biofilms can demonstrate an elevated capacity to withstand substantially higher concentrations of antifungal agents, contrasted with infectious diseases caused by planktonic cells. This inherent resilience intrinsic to biofilm-associated infections engenders a formidable impediment to effective therapeutic interventions. The different mechanisms that are associated with the intrinsic resistance of Candida species encompass drug sequestration by the matrix, drug efflux pumps, stress response cell density, and the presence of persister cells. These persisters, a subset of fungi capable of surviving hostile conditions, pose a remarkable challenge in clinical settings in virtue of their resistance to conventional antifungal therapies. Hence, an exigent imperative has arisen for the development of novel antifungal therapeutics with specific targeting capabilities focused on these pathogenic persisters. On a global scale, fungal persistence and their resistance within biofilms generate an urgent clinical need for investigating recently introduced therapeutic strategies. This review delves into the unique characteristics of Mesenchymal stem/stromal cells (MSCs) and their secreted exosomes, which notably exhibit immunomodulatory and regenerative properties. By comprehensively assessing the current literature and ongoing research in this field, this review sheds light on the plausible mechanisms by which MSCs and their exosomes can be harnessed to selectively target fungal persisters. Additionally, prospective approaches in the use of cell-based therapeutic modalities are examined, emphasizing the importance of further research to overcome the enigmatic fungal persistence.

Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer: a randomized double-blind controlled trial

Wound healing in DFU (diabetic foot ulcer) has prolonged inflammation phase and defective granulation tissue formation. LL-37 has antimicrobial property, induces angiogenesis, and keratinocyte migration and proliferation. This study analyzes the efficacy of LL-37 cream in enhancing wound healing rate and decreasing the levels of IL-1α, TNF-α, and the number of aerobic bacteria colonization in DFU with mild infection. This study was conducted from January 2020 to June 2021 in Jakarta. Subjects were instructed to apply either LL-37 cream or placebo cream twice a week for 4 weeks. Wounds were measured on days 7, 14, 21, and 28 and processed with ImageJ. The levels of LL-37, IL-1α, and TNF-α from wound fluid were measured using ELISA. The number of aerobic bacteria colonization was counted from the isolate grown in culture. The levels of LL-37 in DFU at baseline were equally low in both groups which were 1.07 (0.37-4.96) ng/mg protein in the LL-37 group and 1.11 (0.24-2.09) ng/mg protein in the placebo group. The increase in granulation index was consistently greater in the LL-37 group on days 7, 14, 21, and 28 (p = 0.031, 0.009, 0.006, and 0.037, respectively). The levels of IL-1α and TNF-α increased in both groups on days 14 and 21 (p > 0.05). The decrease in the number of aerobic bacteria colonization was greater in the LL-37 group on days 7, 14 and 21, but greater in the placebo group on day 28 (p > 0.05). In conclusion, LL-37 cream enhanced the healing rate of DFU with mild infection, but did not decrease the levels of IL-1α and TNF-α and the number of aerobic bacteria colonization. This trial is registered at ClinicalTrials.gov, number NCT04098562.

Gene Expression of Human Beta-Defensin-3 and Cathelicidin in the Skin of Leprosy Patients, Household Contacts, and Healthy Individuals from Indonesia

Background

Leprosy, a chronic infectious peripheral neuropathy, is caused by Mycobacterium leprae. This bacterium produces triacylated lipopeptides that can induce the immune system via the Toll-like receptor 2/1 (TLR 2/1) complex. Activation of TLR 2/1 produces proinflammatory cytokines and antimicrobial peptides (AMPs), including human beta-defensin-3 (HBD-3) and cathelicidin.

Purpose

To analyze differences in gene expression of HBD-3 and cathelicidin in the skin of leprosy patients, household contacts, and healthy individuals.

Patients and Methods

An analytic observational study was conducted at the Outpatient Clinic of Dermatology and Venereology of Dr Mohammad Hoesin General Hospital, Palembang, Indonesia, from January 2021 to June 2022. In each group of 18 subjects, 72 samples were collected, including skin lesion in leprosy patients, normal skin in leprosy patients, household contacts, and healthy individuals. A comparison of HBD-3 and cathelicidin gene expression between the four groups was analyzed using Pearson Chi Square, Kruskal-Wallis, and Mann-Whitney Test.

Results

The median value of HBD-3 gene expression on skin lesion in leprosy patients was 260.61 (0.19-3734.10); normal skin in leprosy patients was 1.91 (0.01-151.17); household contacts skin was 7.93 (0.27-121.10); and healthy individuals' skin was 1.00 (1.00-1.00) is highly significant difference (p < 0.0001). The median value of cathelicidin gene expression on skin lesion in leprosy patients was 38.72 (0.28-1852.17); normal skin in leprosy patients was 0.48 (0.01-15.83); household contacts skin was 9.8 (0.04-128.0); and healthy individual skin was 1.00 (1.00-1.00), also highly significant difference (p < 0.0001).

Conclusion

Gene expression of HBD-3 and cathelicidin increased in skin lesions of leprosy patients and household contacts.

Perspective insights of small molecules, phytoconstituents and biologics in the management of psoriasis: A focus on targeting major inflammatory cytokine pathways

Psoriasis is an enduring, pruritic and papulosquamous skin ailment that poses a significant burden on public health. It is mainly characterized by hyperkeratosis, acanthosis, parakeratosis, scaly and erythematous plaques. Biomarkers like interleukin-17, interleukin-12 and -23 and tumor necrosis factor-α serve as key drivers of psoriatic pathogenesis. Triggered release of pro-inflammatory cytokines from various up-regulated pathways leads to psoriatic inflammation. Several target moieties like biologics, small molecules and herbal moieties play a fundamental role in the repression of pathogenesis of psoriasis. Biologics and small molecules engaged in the management of psoriasis have been emphasized in detail. An insight into nano-carrier interventions on herbal moieties and clinical aspects of psoriasis are also highlighted. This review emphasizes various pathological targets involved in psoriasis.

Purification of PaTx-II from the Venom of the Australian King Brown Snake and Characterization of Its Antimicrobial and Wound Healing Activities

Infections caused by multi-drug-resistant (MDR) bacteria are a global threat to human health. As venoms are the source of biochemically diverse bioactive proteins and peptides, we investigated the antimicrobial activity and murine skin infection model-based wound healing efficacy of a 13 kDa protein. The active component PaTx-II was isolated from the venom of Pseudechis australis (Australian King Brown or Mulga Snake). PaTx-II inhibited the growth of Gram-positive bacteria in vitro, with moderate potency (MICs of 25 µM) observed against S. aureus, E. aerogenes, and P. vulgaris. The antibiotic activity of PaTx-II was associated with the disruption of membrane integrity, pore formation, and lysis of bacterial cells, as evidenced by scanning and transmission microscopy. However, these effects were not observed with mammalian cells, and PaTx-II exhibited minimal cytotoxicity (CC50 > 1000 µM) toward skin/lung cells. Antimicrobial efficacy was then determined using a murine model of S. aureus skin infection. Topical application of PaTx-II (0.5 mg/kg) cleared S. aureus with concomitant increased vascularization and re-epithelialization, promoting wound healing. As small proteins and peptides can possess immunomodulatory effects to enhance microbial clearance, cytokines and collagen from the wound tissue samples were analyzed by immunoblots and immunoassays. The amounts of type I collagen in PaTx-II-treated sites were elevated compared to the vehicle controls, suggesting a potential role for collagen in facilitating the maturation of the dermal matrix during wound healing. Levels of the proinflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and interleukin-10 (IL-10), factors known to promote neovascularization, were substantially reduced by PaTx-II treatment. Further studies that characterize the contributions towards efficacy imparted by in vitro antimicrobial and immunomodulatory activity with PaTx-II are warranted.

Induction of psoriasis- and atopic dermatitis-like phenotypes in 3D skin equivalents with a fibroblast-derived matrix

Skin homeostasis is a complex regulated process relying on the crosstalk of keratinocytes, fibroblasts and immune cells. Imbalances of T-cell subsets and the cytokine environment can lead to inflammatory skin diseases such as psoriasis (Ps) and atopic dermatitis (AD). Modern tissue engineering provides several in vitro models mimicking Ps and AD phenotypes. However, these models are either limited in their pathological features, life span, sample availability, reproducibility, controlled handling or simplicity. Some models further lack intensive characterization as they solely focus on differentiation and proliferation aspects. This study introduces a self-assembly model in which the pathological T-cell-signalling of Ps and AD was simulated by subcutaneous Th1 and Th2 cytokine stimulation. The self-established dermal fibroblast-derived matrices of these models were hypothesized to be beneficial for proximal cytokine signalling on epidermal keratinocytes. Comprehensive histological and mRNA analyses of the diseased skin models showed a weakened barrier, distinct differentiation defects, reduced cellular adhesion, inflammation and parakeratosis formation. A keratin shift of declining physiological cytokeratin-10 (CK10) towards increasing inflammatory CK16 was observed upon Th1 or Th2 stimulation. Antimicrobial peptides (AMPs) were upregulated in Ps and downregulated in AD models. The AD biomarker genes CA2, NELL2 and CCL26 were further induced in AD. While Ps samples featured basal hyperproliferation, cells in AD models displayed apoptotic signs. In accordance, these well-controllable three-dimensional in vitro models exhibited Ps and AD-like phenotypes with a high potential for disease research and therapeutic drug testing.

Deciphering the Function of New Therapeutic Targets and Prospective Biomarkers in the Management of Psoriasis

Psoriasis is an immune-mediated skin condition affecting people worldwide, presenting at any age, and leading to a substantial burden physically and mentally. The innate and adaptive immune systems interact intricately with the pathomechanisms that underlie disease. T cells can interact with keratinocytes, macrophages, and dendritic cells through the cytokines they secrete. According to recent research, psoriasis flare-ups can cause systemic inflammation and various other co-morbidities, including depression, psoriatic arthritis, and cardio-metabolic syndrome. Additionally, several auto-inflammatory and auto-immune illnesses may be linked to psoriasis. Although psoriasis has no proven treatment, care must strive by treating patients as soon as the disease surfaces, finding and preventing concurrent multimorbidity, recognising and reducing bodily and psychological distress, requiring behavioural modifications, and treating each patient individually. Biomarkers are traits that are assessed at any time along the clinical continuum, from the early stages of a disease through the beginning of treatment (the foundation of precision medicine) to the late stages of treatment (outcomes and endpoints). Systemic therapies that are frequently used to treat psoriasis provide a variety of outcomes. Targeted therapy selection, better patient outcomes, and more cost-effective healthcare would be made possible by biomarkers that reliably predict effectiveness and safety. This review is an attempt to understand the role of Antimicrobial peptides (AMP), Interleukin-38 (IL-38), autophagy 5 (ATG5) protein and squamous cell carcinoma antigen (SCCA) as biomarkers of psoriasis.

Antimicrobial Peptides with Anti-Candida Activity

Mycoses are accountable for millions of infections yearly worldwide. Invasive candidiasis is the most usual, presenting a high morbidity and mortality. Candida albicans remains the prevalent etiologic agent, but the incidence of other species such as Candida parapsilosis, Candida glabrata and Candida auris keeps increasing. These pathogens frequently show a reduced susceptibility to commonly used antifungal drugs, including polyenes, triazoles and echinocandins, and the incidence of emerging multi-drug-resistant strains of these species continues to increase. Therefore, the need to search for new molecules that target these pathogenic species in a different manner is now more urgent than ever. Nature is an almost endless source of interesting new molecules that could meet this need. Among these molecules, antimicrobial peptides, present in different sources in nature, possess some advantages over conventional antifungal agents, even with their own drawbacks, and are considered as a promising pharmacological option against a wide range of microbial infections. In this review, we describe 20 antimicrobial peptides from different origins that possess an activity against Candida.

Potential of Mesenchymal Stem Cell-Derived Exosomes as a Novel Treatment for Female Infertility Caused by Bacterial Infections

Neisseria gonorrhoeae and Chlamydia trachomatis are the most common causes of bacterial sexually transmitted diseases (STDs) with complications in women, including pelvic inflammatory disease (PID), ectopic pregnancy, and infertility. The main concern with these infections is that 70% of infected women are asymptomatic and these infections ascend to the upper female reproductive tract (FRT). Primary infection in epithelial cells creates a cascade of events that leads to secretion of pro-inflammatory cytokines that stimulate innate immunity. Production of various cytokines is damaging to mucosal barriers, and tissue destruction leads to ciliated epithelial destruction that is associated with tubal scarring and ultimately provides the conditions for infertility. Mesenchymal stem cells (MSCs) are known as tissue specific stem cells with limited self-renewal capacity and the ability to repair damaged tissues in a variety of pathological conditions due to their multipotential differentiation capacity. Moreover, MSCs secrete exosomes that contain bioactive factors such as proteins, lipids, chemokines, enzymes, cytokines, and immunomodulatory factors which have therapeutic properties to enhance recovery activity and modulate immune responses. Experimental studies have shown that local and systemic treatment of MSC-derived exosomes (MSC-Exos) suppresses the destructive immune response due to the delivery of immunomodulatory proteins. Interestingly, some recent data have indicated that MSC-Exos display strong antimicrobial effects, by the secretion of antimicrobial peptides and proteins (AMPs), and increase bacterial clearance by enhancing the phagocytic activity of host immune cells. Considering MSC-Exos can secrete different bioactive factors that can modulate the immune system and prevent infection, exosome therapy is considered as a new therapeutic method in the treatment of inflammatory and microbial diseases. Here we intend to review the possible application of MSC-Exos in female reproductive system bacterial diseases.

Alarmins/stressorins and immune dysregulation in intractable skin disorders

Unlike other barrier epithelia of internal organs, the stratified squamous epithelium of the skin is always exposed to the external environment. However, the robust barrier structure and function of the skin are highly resistant against external insults so as to not easily allow foreign invasions. Upon sensing danger signals, the innate immunity system is promptly activated. This process is mediated by alarmins, which are released passively from damaged cells. Nuclear alarmins or stressorins are actively released from intact cells in response to various cellular stresses. Alarmins/stressorins are deeply involved in the disease processes of chronic skin disorders of an unknown cause, such as rosacea, psoriasis, and atopic dermatitis. Furthermore, alarmins/stressorins are also induced in the congenital skin disorders of ichthyosis and keratoderma due to defective keratinization. Studies on alarmin activation and its downstream pathways may help develop novel therapeutic agents for intractable skin disorders.

Antimicrobial peptides and proteins: Interaction with the skin microbiota

The cutaneous microbiota comprises all living skin microorganisms. There is increasing evidence that the microbiota plays a crucial role in skin homeostasis. Accordingly, a dysbiosis of the microbiota may trigger cutaneous inflammation. The need for a balanced microbiota requires specific regulatory mechanisms that control and shape the microbiota. In this review, we highlight the present knowledge suggesting that antimicrobial peptides (AMPs) may exert a substantial influence on the microbiota by controlling their growth. This is supported by own data showing the differential influence of principal skin-derived AMPs on commensal staphylococci. Vice versa, we also illuminate how the cutaneous microbiota interacts with skin-derived AMPs by modulating AMP expression and how microbiota members protect themselves from the antimicrobial activity of AMPs. Taken together, the current picture suggests that a fine-tuned and well-balanced AMP-microbiota interplay on the skin surface may be crucial for skin health.

Antimicrobial Peptides: A New Hope in Biomedical and Pharmaceutical Fields

Antibiotics are essential drugs used to treat pathogenic bacteria, but their prolonged use contributes to the development and spread of drug-resistant microorganisms. Antibiotic resistance is a serious challenge and has led to the need for new alternative molecules less prone to bacterial resistance. Antimicrobial peptides (AMPs) have aroused great interest as potential next-generation antibiotics, since they are bioactive small proteins, naturally produced by all living organisms, and representing the first line of defense against fungi, viruses and bacteria. AMPs are commonly classified according to their sources, which are represented by microorganisms, plants and animals, as well as to their secondary structure, their biosynthesis and their mechanism of action. They find application in different fields such as agriculture, food industry and medicine, on which we focused our attention in this review. Particularly, we examined AMP potential applicability in wound healing, skin infections and metabolic syndrome, considering their ability to act as potential Angiotensin-Converting Enzyme I and pancreatic lipase inhibitory peptides as well as antioxidant peptides. Moreover, we argued about the pharmacokinetic and pharmacodynamic approaches to develop new antibiotics, the drug development strategies and the formulation approaches which need to be taken into account in developing clinically suitable AMP applications.

Complementary Effects of Carbamylated and Citrullinated LL37 in Autoimmunity and Inflammation in Systemic Lupus Erythematosus

LL37 acts as T-cell/B-cell autoantigen in Systemic lupus erythematosus (SLE) and psoriatic disease. Moreover, when bound to "self" nucleic acids, LL37 acts as "danger signal," leading to type I interferon (IFN-I)/pro-inflammatory factors production. T-cell epitopes derived from citrullinated-LL37 act as better antigens than unmodified LL37 epitopes in SLE, at least in selected HLA-backgrounds, included the SLE-associated HLA-DRB1*1501/HLA-DRB5*0101 backgrounds. Remarkably, while "fully-citrullinated" LL37 acts as better T-cell-stimulator, it loses DNA-binding ability and the associated "adjuvant-like" properties. Since LL37 undergoes a further irreversible post-translational modification, carbamylation and antibodies to carbamylated self-proteins other than LL37 are present in SLE, here we addressed the involvement of carbamylated-LL37 in autoimmunity and inflammation in SLE. We detected carbamylated-LL37 in SLE-affected tissues. Most importantly, carbamylated-LL37-specific antibodies and CD4 T-cells circulate in SLE and both correlate with disease activity. In contrast to "fully citrullinated-LL37," "fully carbamylated-LL37" maintains both innate and adaptive immune-cells' stimulatory abilities: in complex with DNA, carbamylated-LL37 stimulates plasmacytoid dendritic cell IFN-α production and B-cell maturation into plasma cells. Thus, we report a further example of how different post-translational modifications of a self-antigen exert complementary effects that sustain autoimmunity and inflammation, respectively. These data also show that T/B-cell responses to carbamylated-LL37 represent novel SLE disease biomarkers.

Antimicrobial Peptides: a New Frontier in Antifungal Therapy

Invasive fungal infections in humans are generally associated with high mortality, making the choice of antifungal drug crucial for the outcome of the patient. The limited spectrum of antifungals available and the development of drug resistance represent the main concerns for the current antifungal treatments, requiring alternative strategies. Antimicrobial peptides (AMPs), expressed in several organisms and used as first-line defenses against microbial infections, have emerged as potential candidates for developing new antifungal therapies, characterized by negligible host toxicity and low resistance rates. Most of the current literature focuses on peptides with antibacterial activity, but there are fewer studies of their antifungal properties. This review focuses on AMPs with antifungal effects, including their in vitro and in vivo activities, with the biological repercussions on the fungal cells, when known. The classification of the peptides is based on their mode of action: although the majority of AMPs exert their activity through the interaction with membranes, other mechanisms have been identified, including cell wall inhibition and nucleic acid binding. In addition, antifungal compounds with unknown modes of action are also described. The elucidation of such mechanisms can be useful to identify novel drug targets and, possibly, to serve as the templates for the synthesis of new antimicrobial compounds with increased activity and reduced host toxicity.

New Treatment Addressing the Pathogenesis of Psoriasis

Psoriasis is an immune cell-mediated inflammatory skin disease. The interleukin (IL)23/IL17 axis plays an important role in the development of psoriasis. The effectiveness of biologic treatments such as tumor necrosis factor (TNF)α inhibitors (infliximab, adalimumab, certolizumab pegol), IL23 inhibitors (ustekinumab, guselkumab, tildrakizumab, risankizumab), and IL17 inhibitors (secukinumab, ixekizumab, brodalumab) have verified these findings. Immune-related cells such as dendritic cells (DCs) and macrophages, in addition to Toll-like receptors and cytokines such as interferon (IFN)α, TNFα, IFNɤ, IL12, IL22, IL23, and IL17, are related to the pathogenesis of psoriasis. Here, we first review new insights regarding the pathogenesis of psoriasis, as it relates to DCs, Langerhans cells, macrophages, the signal transducer and activator of transcription 3 pathway, and aryl hydrocarbon receptor in cutaneous vascular endothelial cells. Based on these findings, we summarize currently available oral treatments and biologics. Furthermore, we describe a new treatment option including Janus kinase inhibitor, tyrosine kinase 2 inhibitor, modulator of sphingosine 1-phosphate receptor 1, and Rho-associated kinase 2 inhibitor.

Psoriasis and Antimicrobial Peptides

Psoriasis is a systemic inflammatory disease caused by crosstalk between various cells such as T cells, neutrophils, dendritic cells, and keratinocytes. Antimicrobial peptides (AMPs) such as β-defensin, S100, and cathelicidin are secreted from these cells and activate the innate immune system through various mechanisms to induce inflammation, thus participating in the pathogenesis of psoriasis. In particular, these antimicrobial peptides enhance the binding of damage-associated molecular patterns such as self-DNA and self-RNA to their receptors and promote the secretion of interferon from activated plasmacytoid dendritic cells and keratinocytes to promote inflammation in psoriasis. Neutrophil extracellular traps (NETs), complexes of self-DNA and proteins including LL-37 released from neutrophils in psoriatic skin, induce Th17. Activated myeloid dendritic cells secrete a mass of inflammatory cytokines such as IL-12 and IL-23 in psoriasis, which is indispensable for the proliferation and survival of T cells that produce IL-17. AMPs enhance the production of some of Th17 and Th1 cytokines and modulate receptors and cellular signaling in psoriasis. Inflammation induced by DAMPs, including self-DNA and RNA released due to microinjuries or scratches, and the enhanced recognition of DAMPs by AMPs, may be involved in the mechanism underlying the Köbner phenomenon in psoriasis.

Generation of Monoclonal Antibodies Specific for Native LL37 and Citrullinated LL37 That Discriminate the Two LL37 Forms in the Skin and Circulation of Cutaneous/Systemic Lupus Erythematosus and Rheumatoid Arthritis Patients

Human cathelicidin LL37 is a cationic antimicrobial peptide active against bacteria and viruses and exerting immune modulatory functions. LL37 can be also a target of autoreactive B- and T-lymphocytes in autoimmune settings. Irreversible post-translational modifications, such as citrullination and carbamylation, mainly occurring at the level of cationic amino acids arginine and lysine, can affect the inflammatory properties and reduce antibacterial effects. Moreover, these modifications could be implicated in the rupture of immune tolerance to LL37 in chronic conditions such as psoriatic disease and cutaneous lupus (LE)/systemic lupus erythematosus (SLE). Here, we describe the generation and fine specificity of six recombinant antibodies (MRB137–MRB142), produced as a monovalent mouse antibody with the antigen-binding scFv portion fused to a mouse IgG2a Fc, and their ability to recognize either native or citrullinated LL37 (cit-LL37) and not cross-react to carbamylated LL37. By using these antibodies, we detected native LL37 or cit-LL37 in SLE and rheumatoid arthritis (RA) sera, and in LE skin, by ELISA and immunohistochemistry, respectively. Such antibodies represent previously unavailable and useful tools to address relationships between the presence of post-translational modified LL37 and the immune system status (in terms of innate/adaptive responses activation) and the clinical characteristics of patients affected by chronic immune-mediated diseases or infectious diseases.

Native/citrullinated LL37-specific T-cells help autoantibody production in Systemic Lupus Erythematosus

LL37 exerts a dual pathogenic role in psoriasis. Bound to self-DNA/RNA, LL37 licenses autoreactivity by stimulating plasmacytoid dendritic cells-(pDCs)-Type I interferon (IFN-I) and acts as autoantigen for pathogenic Th17-cells. In systemic lupus erythematosus (SLE), LL37 also triggers IFN-I in pDCs and is target of pathogenic autoantibodies. However, whether LL37 activates T-cells in SLE and how the latter differ from psoriasis LL37-specific T-cells is unknown. Here we found that 45% SLE patients had circulating T-cells strongly responding to LL37, which correlate with anti-LL37 antibodies/disease activity. In contrast to psoriatic Th17-cells, these LL37-specific SLE T-cells displayed a T-follicular helper-(T_FH)-like phenotype, with CXCR5/Bcl-6 and IL-21 expression, implicating a role in stimulation of pathogenic autoantibodies. Accordingly, SLE LL37-specific T-cells promoted B-cell secretion of pathogenic anti-LL37 antibodies in vitro. Importantly, we identified abundant citrullinated LL37 (cit-LL37) in SLE tissues (skin and kidney) and observed very pronounced reactivity of LL37-specific SLE T-cells to cit-LL37, compared to native-LL37, which was much more occasional in psoriasis. Thus, in SLE, we identified LL37-specific T-cells with a distinct functional specialization and antigenic specificity. This suggests that autoantigenic specificity is independent from the nature of the autoantigen, but rather relies on the disease-specific milieu driving T-cell subset polarization and autoantigen modifications.

Antimicrobial Peptides as Anti-Infective Agents in Pre-Post-Antibiotic Era?

Resistance to antibiotics is one of the main current threats to human health and every year multi-drug resistant bacteria are infecting millions of people worldwide, with many dying as a result. Ever since their discovery, some 40 years ago, the antimicrobial peptides (AMPs) of innate defense have been hailed as a potential alternative to conventional antibiotics due to their relatively low potential to elicit resistance. Despite continued effort by both academia and start-ups, currently there are still no antibiotics based on AMPs in use. In this study, we discuss what we know and what we do not know about these agents, and what we need to know to successfully translate discovery to application. Understanding the complex mechanics of action of these peptides is the main prerequisite for identifying and/or designing or redesigning novel molecules with potent biological activity. However, other aspects also need to be well elucidated, i.e., the (bio)synthetic processes, physiological and pathological contexts of their activity, and a quantitative understanding of how physico-chemical properties affect activity. Research groups worldwide are using biological, biophysical, and algorithmic techniques to develop models aimed at designing molecules with the necessary blend of antimicrobial potency and low toxicity. Shedding light on some open questions may contribute toward improving this process.

The Antimicrobial and Immunomodulatory Function of RNase 7 in Skin

The human ribonuclease RNase 7 has been originally isolated from human skin and is a member of the human RNase A superfamily. RNase 7 is constantly released by keratinocytes and accumulates on the skin surface. The expression of RNase 7 in keratinocytes can be induced by diverse stimuli such as cytokines, growth factors, and microbial factors. RNase 7 exhibits a potent broad spectrum of antimicrobial activity against various microorganisms and contributes to control bacterial growth on the skin surface. The ribonuclease and antimicrobial activity of RNase 7 can be blocked by the endogenous ribonuclease inhibitor. There is also increasing evidence that RNase 7 exerts immunomodulatory activities and may participate in antiviral defense. In this review, we discuss how these characteristics of RNase 7 contribute to innate cutaneous defense and highlight its role in skin infection and inflammation. We also speculate how a potential dysregulation of RNase 7 promotes inflammatory skin diseases and if RNase 7 may have therapeutic potential.

[Psoriasis and the microbiome]

BACKGROUND

Psoriasis is a frequent chronic inflammatory systemic disease. It is associated with changes in the microbiome, which may trigger psoriasis and influence the course of the disease.

OBJECTIVE

Current methods for detection and the potential role of the microbiome in the pathogenesis of psoriasis are described.

MATERIAL AND METHODS

A literature search was conducted using the databases Medline and PubMed as well as a general internet and book research.

RESULTS

Both skin and gut microbiota are involved in the immunopathogenesis and may substantially modulate psoriasis. Antimicrobial peptides may serve as a link between the microbiome and the immunological mechanisms in psoriasis by regulating the microbiome at interfaces and can trigger psoriasis as antigens. Recent innovative methods, such as 16S rRNA next-generation sequencing significantly facilitate microbiome analysis.

CONCLUSION

The analysis of the microbiome in patients with psoriasis before, during and after treatment provides a basis for the identification of potential biomarkers for predicting individual treatment responses and facilitating the decision for a certain treatment.

Severity, heterogeneity and systemic inflammation in psoriasis

Psoriasis may express as active severe disease or as mild stable disease. In particular, patients with active severe disease present systemic involvement, including comorbidities and increased values of parameters reflecting an active state of innate immunity. In contrast, patients with mild stable disease show a dominancy of acquired immunity. In this review article, we report the clinical aspects of disease manifestations of both active and quiescent psoriasis as well as the immunological aspects, as well as the impact on antimicrobial resistance. The activity of psoriasis is not captured in the present outcome measures for severity assessment. The present review suggests that incorporating disease activity may be important in the assessment of the efficacy of treatments.

Cationic Intrinsically Disordered Antimicrobial Peptides (CIDAMPs) Represent a New Paradigm of Innate Defense with a Potential for Novel Anti-Infectives

In the search for potential mechanisms underlying the remarkable resistance of healthy skin against infection by soil bacteria like Pseudomonas (P.) aeruginosa we identified fragments of the intrinsically disordered protein hornerin as potent microbicidal agents in the stratum corneum. We found that, independent of the amino acid (AA)-sequence, any tested linear cationic peptide containing a high percentage of disorder-promoting AA and a low percentage of order-promoting AA is a potent microbicidal antimicrobial. We further show that the antimicrobial activity of these cationic intrinsically disordered antimicrobial peptides (CIDAMPs) depends on the peptide chain length, its net charge, lipidation and environmental conditions. The ubiquitous presence of latent CIDAMP sources in nature suggests a common and yet overlooked adapted innate disinfection system of body surfaces. The simple structure and virtually any imaginable sequence or composition of disorder-promoting AA allow the generation of a plethora of CIDAMPs. These are potential novel microbicidal anti-infectives for various bacterial pathogens, including P. aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA) and fungal pathogens like Candida albicans and Cryptococcus neoformans.

Endogenous Antimicrobial Peptide Expression in Response to Bacterial Epidermal Colonization

Bacterial commensal colonization of human skin is vital for the training and maintenance of the skin’s innate and adaptive immune functions. In addition to its physical barrier against pathogen colonization, the skin expresses a variety of antimicrobial peptides (AMPs) which are expressed constitutively and induced in response to pathogenic microbial stimuli. These AMPs are differentially effective against a suite of microbial skin colonizers, including both bacterial and fungal residents of the skin. We review the breadth of microorganism-induced cutaneous AMP expression studies and their complementary findings on the efficacy of skin AMPs against different bacterial and fungal species. We suggest further directions for skin AMP research based on emerging skin microbiome knowledge in an effort to advance our understanding of the nuanced host–microbe balance on human skin. Such advances should enable the scientific community to bridge the gap between descriptive disease-state AMP studies and experimental single-species in vitro studies, thereby enabling research endeavors that more closely mimic the natural skin environs.

RNase 7 downregulates TH2 cytokine production by activated human T cells

BACKGROUND

The antimicrobial peptide (AMP) RNase 7 is constitutively expressed in the epidermis of healthy human skin and has been found to be upregulated in chronic inflammatory skin diseases such as atopic dermatitis and psoriasis. Activated T cells in lesional skin of patients with atopic dermatitis (AD) and psoriasis (PSO) might be directly exposed to RNase 7. In addition to their antimicrobial activity, immunoregulatory functions have been published for several AMPs. In this study, we investigated immunoregulatory effects of the antimicrobial peptide RNase 7 on activated T cells.

METHODS

Isolated human CD3+T cells were stimulated with RNase 7 and screened for possible effects by mRNA microarray analysis. The results of the mRNA microarray were confirmed in isolated CD4+T cells and in polarized TH2 cells using skin-derived native RNase 7 and a recombinant ribonuclease-inactive RNase 7 mutant. Activation of GATA3 was analysed by electrophoretic mobility shift assay.

RESULTS

Treatment of activated human CD4+T cells and TH2 cells with RNase 7 selectively reduced the expression of TH2 cytokines (IL-13, IL-4 and IL-5). Experiments with a ribonuclease-inactive recombinant RNase 7 mutant showed that RNase 7 ribonuclease activity is dispensable for the observed regulatory effect. We further demonstrate that CD4+T cells from AD patients revealed a significantly less pronounced downregulation of IL-13 in response to RNase 7 compared to healthy control. Finally, we show that GATA3 activation was diminished upon cultivation of T cells with RNase 7.

CONCLUSION

Our data indicate that RNase 7 has immunomodulatory functions on TH2 cells and decreases the production of TH2 cytokines in the skin.

Pathogen-Host Defense in the Evolution of Depression: Insights into Epidemiology, Genetics, Bioregional Differences and Female Preponderance

Significant attention has been paid to the potential adaptive value of depression as it relates to interactions with people in the social world. However, in this review, we outline the rationale of why certain features of depression including its environmental and genetic risk factors, its association with the acute phase response and its age of onset and female preponderance appear to have evolved from human interactions with pathogens in the microbial world. Approaching the relationship between inflammation and depression from this evolutionary perspective yields a number of insights that may reveal important clues regarding the origin and epidemiology of the disorder as well as the persistence of its risk alleles in the modern human genome.

The Ribonuclease A Superfamily in Humans: Canonical RNases as the Buttress of Innate Immunity

In humans, the ribonuclease A (RNase A) superfamily contains eight different members that have RNase activities, and all of these members are encoded on chromosome 14. The proteins are secreted by a large variety of different tissues and cells; however, a comprehensive understanding of these proteins’ physiological roles is lacking. Different biological effects can be attributed to each protein, including antiviral, antibacterial and antifungal activities as well as cytotoxic effects against host cells and parasites. Different immunomodulatory effects have also been demonstrated. This review summarizes the available data on the human RNase A superfamily and illustrates the significant role of the eight canonical RNases in inflammation and the host defence system against infections.

Risk factors for MRSA colonization in dermatologic patients in Germany

BACKGROUND AND OBJECTIVES

Detection of methicillin-resistant Staphylococcus aureus (MRSA) carriage requires well-defined risk factors (RFs). Except for "chronic wounds", RFs are mostly specified in national recommendations. To avoid ineffective and expensive screening, we divided the entity "wounds" into different categories and calculated further RFs in dermatologic patients.

PATIENTS AND METHODS

After a surveillance period with general MRSA screening, we correlated MRSA results with wound categories and dermatologically relevant diagnoses. We analyzed the screening efficacy by adding potential new RFs.

RESULTS

Ulcers (pressure, arterial, combined pressure/arterial ulcers, ulcers otherwise unclassified), type 2 diabetes mellitus (DM), and atopic dermatitis (AD) were significantly associated with MRSA carriage. Tumors (subgroup basal and squamous cell carcinoma) were also significantly associated with MRSA carriage but had a protective odds ratio. Differentiation of wound types did not provide added benefit. In all MRSA-positive patients with chronic wounds, other RKI-listed RFs or type 2 DM were found. Screening sensitivity was increased combining classic RFs (except wounds) with type 2 DM and AD.

CONCLUSIONS

In dermatologic patients, AD and type 2 DM were identified as new RFs. Distinct wound types were also found to be significant RFs, but differentiated screening offers no benefit. When screening patients according to national recommendations, excluding wounds but including type 2 DM and AD, there is no loss of sensitivity.

Molecular Basis of the Receptor Interactions of Polysialic Acid (polySia), polySia Mimetics, and Sulfated Polysaccharides

Polysialic acid (polySia) and polySia glycomimetic molecules support nerve cell regeneration, differentiation, and neuronal plasticity. With a combination of biophysical and biochemical methods, as well as data mining and molecular modeling techniques, it is possible to correlate specific ligand-receptor interactions with biochemical processes and in vivo studies that focus on the potential therapeutic impact of polySia, polySia glycomimetics, and sulfated polysaccharides in neuronal diseases. With this strategy, the receptor interactions of polySia and polySia mimetics can be understood on a submolecular level. As the HNK-1 glycan also enhances neuronal functions, we tested whether similar sulfated oligo- and polysaccharides from seaweed could be suitable, in addition to polySia, for finding potential new routes into patient care focusing on an improved cure for various neuronal diseases. The knowledge obtained here on the structural interplay between polySia or sulfated polysaccharides and their receptors can be exploited to develop new drugs and application routes for the treatment of neurological diseases and dysfunctions.

RNase 7 in Cutaneous Defense

RNase 7 belongs to the RNase A superfamily and exhibits a broad spectrum of antimicrobial activity against various microorganisms. RNase 7 is expressed in human skin, and expression in keratinocytes can be induced by cytokines and microbes. These properties suggest that RNase 7 participates in innate cutaneous defense. In this review, we provide an overview about the role of RNase 7 in cutaneous defense with focus on the molecular mechanism of the antimicrobial activity of RNase 7, the regulation of RNase 7 expression, and the role of RNase 7 in skin diseases.

Antimicrobial peptides and wound healing: biological and therapeutic considerations

Repair of tissue wounds is a fundamental process to re-establish tissue integrity and regular function. Importantly, infection is a major factor that hinders wound healing. Multicellular organisms have evolved an arsenal of host-defense molecules, including antimicrobial peptides (AMPs), aimed at controlling microbial proliferation and at modulating the host's immune response to a variety of biological or physical insults. In this brief review, we provide the evidence for a role of AMPs as endogenous mediators of wound healing and their promising therapeutic potential for the treatment of non-life-threatening skin and other epithelial injuries.

The role of antimicrobial peptides in chronic inflammatory skin diseases

Antimicrobial peptides (AMPs) are effector molecules of the innate immune system of the skin. They present an activity against a broad spectrum of Gram-positive and Gram-negative bacteria as well as some fungi, parasites and enveloped viruses. Several inflammatory skin diseases including psoriasis, atopic dermatitis, acne vulgaris and rosacea are characterized by a dysregulated expression of AMPs. Antimicrobial peptides are excessively produced in lesional psoriatic scales or rosacea in contrast to the atopic skin that shows lower AMP levels when compared with psoriasis. The importance of the AMPs contribution to host immunity is indisputable as alterations in the antimicrobial peptide expression have been associated with various pathologic processes. This review discusses the biology and clinical relevance of antimicrobial peptides expressed in the skin and their role in the pathogenesis of inflammatory skin diseases.