Macrophages from patients with atopic dermatitis show a reduced CXCL10 expression in response to staphylococcal α-toxin

Bioinformatics analysis identifies a key gene HLA_DPA1 in severe influenza-associated immune infiltration

BACKGROUND

Severe influenza is a serious global health issue that leads to prolonged hospitalization and mortality on a significant scale. The pathogenesis of this infectious disease is poorly understood. Therefore, this study aimed to identify the key genes associated with severe influenza patients necessitating invasive mechanical ventilation.

METHODS

The current study utilized two publicly accessible gene expression profiles (GSE111368 and GSE21802) from the Gene Expression Omnibus database. The research focused on identifying the genes exhibiting differential expression between severe and non-severe influenza patients. We employed three machine learning algorithms, namely the Least Absolute Shrinkage and Selection Operator regression model, Random Forest, and Support Vector Machine-Recursive Feature Elimination, to detect potential key genes. The key gene was further selected based on the diagnostic performance of the target genes substantiated in the dataset GSE101702. A single-sample gene set enrichment analysis algorithm was applied to evaluate the participation of immune cell infiltration and their associations with key genes.

RESULTS

A total of 44 differentially expressed genes were recognized; among them, we focused on 10 common genes, namely PCOLCE2, HLA_DPA1, LOC653061, TDRD9, MPO, HLA_DQA1, MAOA, S100P, RAP1GAP, and CA1. To ensure the robustness of our findings, we employed overlapping LASSO regression, Random Forest, and SVM-RFE algorithms. By utilizing these algorithms, we were able to pinpoint the aforementioned 10 genes as potential biomarkers for distinguishing between both cases of influenza (severe and non-severe). However, the gene HLA_DPA1 has been recognized as a crucial factor in the pathological condition of severe influenza. Notably, the validation dataset revealed that this gene exhibited the highest area under the receiver operating characteristic curve, with a value of 0.891. The use of single-sample gene set enrichment analysis has provided valuable insights into the immune responses of patients afflicted with severe influenza that have further revealed a categorical correlation between the expression of HLA_DPA1 and lymphocytes.

CONCLUSION

The findings indicated that the HLA_DPA1 gene may play a crucial role in the immune-pathological condition of severe influenza and could serve as a promising therapeutic target for patients infected with severe influenza.

CKBA suppresses mast cell activation via ERK signaling pathway in murine atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disorder. Mast cells play an important role in AD because they regulate allergic reactions and inflammatory responses. However, whether and how the modulation of mast cell activity affects AD has not been determined. In this study, we aimed to determine the effects and mechanisms of 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid (CKBA). This natural compound derivative alleviates skin inflammation by inhibiting mast cell activation and maintaining skin barrier homeostasis in AD. CKBA markedly reduced serum IgE levels and alleviated skin inflammation in calcipotriol (MC903)-induced AD mouse model. CKBA also restrained mast cell degranulation both in vitro and in vivo. RNA-seq analysis revealed that CKBA downregulated the extracellular signal-regulated kinase (ERK) signaling in BM-derived mast cells activated by anti-2,4-dinitrophenol/2,4-dinitrophenol-human serum albumin. We proved that CKBA suppressed mast cell activation via ERK signaling using the ERK activator (t-butyl hydroquinone) and inhibitor (selumetinib; AZD6244) in AD. Thus, CKBA suppressed mast cell activation in AD via the ERK signaling pathway and could be a therapeutic candidate drug for AD.

Blockage of the IL-31 Pathway as a Potential Target Therapy for Atopic Dermatitis

Atopic dermatitis (AD), a pruritic, inflammatory chronic disease with multifactorial pathogenesis, has been a therapeutic challenge. Novel target treatments aim to reduce not only the immunologic dysfunction and microbiome dysbiosis but also the recovery of the damaged skin barrier. The current review focuses on the interleukin 31 (IL-31) pathway and AD and offers an overview of the current clinical studies with monoclonal antibodies blocking this cascade. Pruritus, the key symptom of AD, has substantial participation of the IL-31 complex and activation of relevant signaling pathways. Epidermal keratinocytes, inflammatory cells, and cutaneous peripheral nerves express the interleukin-31 receptor α-chain (IL-31RA), upregulated by Staphylococcus aureus toxins or Th2 cytokines involved in AD. Nemolizumab is a humanized monoclonal antibody that antagonizes IL-31RA, inhibiting the IL-31 cascade and therefore contributing to reducing the pruritus and inflammation and recovering the damaged skin barrier in AD patients. Phases 2 and 3 clinical trials with nemolizumab in AD show a suitable safety profile, with a fast, efficient, and sustained reduction of pruritus and severity scores, especially when associated with topical treatment. Deciphering the full interplay of the IL-31 pathway and AD may expand the potential of nemolizumab as a targeted therapy for AD and other pruritic conditions.

Exploring the Role of Staphylococcus aureus in Inflammatory Diseases

Staphylococcus aureus is a very common Gram-positive bacterium, and S. aureus infections play an extremely important role in a variety of diseases. This paper describes the types of virulence factors involved, the inflammatory cells activated, the process of host cell death, and the associated diseases caused by S. aureus. S. aureus can secrete a variety of enterotoxins and other toxins to trigger inflammatory responses and activate inflammatory cells, such as keratinocytes, helper T cells, innate lymphoid cells, macrophages, dendritic cells, mast cells, neutrophils, eosinophils, and basophils. Activated inflammatory cells can express various cytokines and induce an inflammatory response. S. aureus can also induce host cell death through pyroptosis, apoptosis, necroptosis, autophagy, etc. This article discusses S. aureus and MRSA (methicillin-resistant S. aureus) in atopic dermatitis, psoriasis, pulmonary cystic fibrosis, allergic asthma, food poisoning, sarcoidosis, multiple sclerosis, and osteomyelitis. Summarizing the pathogenic mechanism of Staphylococcus aureus provides a basis for the targeted treatment of Staphylococcus aureus infection.

Airway Macrophage and Dendritic Cell Subsets in the Resting Human Lung

Dendritic cells (DCs) and macrophages (MΦs) are antigen-presenting phagocytic cells found in many peripheral tissues of the human body, including the blood, lymph nodes, skin, and lung. They are vital to maintaining steady-state respiration in the human lung based on their ability to clear airways while also directing tolerogenic or inflammatory responses based on specific stimuli. Over the past three decades, studies have determined that there are multiple subsets of these two general cell types that exist in the airways and interstitium. Identifying these numerous subsets has proven challenging, especially with the unique microenvironments present in the lung. Cells found in the vasculature are not the same subsets found in the skin or the lung, as demonstrated by surface marker expression. By transcriptional profiling, these subsets show similarities but also major differences. Primary human lung cells and/ or tissues are difficult to acquire, particularly in a healthy condition. Additionally, surface marker screening and transcriptional profiling are continually identifying new DC and MΦ subsets. While the overall field is moving forward, we emphasize that more attention needs to focus on replicating the steady-state microenvironment of the lung to reveal the physiological functions of these subsets.

Exploring the Role of Staphylococcus Aureus Toxins in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic and inflammatory skin disease with intense pruritus and xerosis. AD pathogenesis is multifactorial, involving genetic, environmental, and immunological factors, including the participation of Staphylococcus aureus. This bacterium colonizes up to 30-100% of AD skin and its virulence factors are responsible for its pathogenicity and antimicrobial survival. This is a concise review of S. aureus superantigen-activated signaling pathways, highlighting their involvement in AD pathogenesis, with an emphasis on skin barrier disruption, innate and adaptive immunity dysfunction, and microbiome alterations. A better understanding of the combined mechanisms of AD pathogenesis may enhance the development of future targeted therapies for this complex disease.

Recent Advances in Drug-Induced Hypersensitivity Syndrome/Drug Reaction with Eosinophilia and Systemic Symptoms

Drug-induced hypersensitivity syndrome (DIHS), also termed as drug reaction with eosinophilia and systemic symptoms (DRESS), is a multiorgan systemic reaction characterized by a close relationship with the reactivation of herpes virus. Published data has demonstrated that among patients with DIHS/DRESS, 75–95% have leukocytosis, 18.2–90% show atypical lymphocytes, 52–95% have eosinophilia, and 75–100% have hepatic abnormalities. Histologically, eosinophils were observed less frequently than we expected (20%). The mainstay of DIHS/DRESS treatment is a moderate dose of systemic corticosteroids, followed by gradual dose reduction. In this review, we will emphasize that elevations in the levels of several cytokines/chemokines, including tumor necrosis factor- (TNF-) α and the thymus and activation-regulated chemokine (TARC/CCL17), during the early stage of disease, are good markers allowing the early recognition of HHV-6 reactivation. TNF-α and TARC levels also reflect therapeutic responses and may be useful markers of the DIHS disease process. Recently, the pathogenic mechanism of T-cell activation triggered by human leukocyte antigen- (HLA-) restricted presentation of a drug or metabolites was elucidated. Additionally, we recently reported that dapsone would fit within the unique subpocket of the antigen-recognition site of HLA-B^∗13:01. Further studies will render it possible to choose better strategies for DIHS prevention and therapy.

Atopic dermatitis: allergic dermatitis or neuroimmune dermatitis?

Advances in knowledge of neurocellulars relations have provided new directions in the understanding and treatment of numerous conditions, including atopic dermatitis. It is known that emotional, physical, chemical or biological stimuli can generate more accentuated responses in atopic patients than in non-atopic individuals; however, the complex network of control covered by these influences, especially by neuropeptides and neurotrophins, and their genetic relations, still keep secrets to be revealed. Itching and airway hyperresponsiveness, the main aspects of atopy, are associated with disruption of the neurosensory network activity. Increased epidermal innervation and production of neurotrophins, neuropeptides, cytokines and proteases, in addition to their relations with the sensory receptors in an epidermis with poor lipid mantle, are the aspects currently covered for understanding atopic dermatitis.

Cellular responses to Staphylococcus aureus alpha-toxin in chronic rhinosinusitis with nasal polyps

BACKGROUND

In contrast to Staphylococcus aureus-derived superantigenic exotoxins, the role of non-superantigenic exotoxins in the pathogenesis of eosinophilic airway diseases remains obscure. We sought to characterize S. aureus alpha-toxin-induced cellular responses in chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

Dispersed nasal polyp cells and uncinate tissue cells were prepared from patients with CRS with and without nasal polyps, respectively. Cells were incubated with various concentrations of alpha-toxin or staphylococcal enterotoxin B and then the levels of IL-5, IL-13, IFN-γ, IL-17A, and IL-10 in the cell supernatants were determined. The pathophysiological significance of alpha-toxin-induced cytokine production was also determined including radiological severity of rhinosinusitis, tissue and blood eosinophilia, serum total IgE level, and 1-s forced expiratory volume/forced vital capacity ratio (FEV1/FVC).

RESULTS

Nasal polyp cells produced substantial amounts of IL-5, IL-13, IFN-γ, IL-17A, and IL-10 in response to alpha-toxin. Cytokine production was higher in nasal polyp cells than in uncinate tissue cells. The potency of alpha-toxin in stimulating IL-5, IL-13, and IL-10 production was comparable to that of enterotoxin. Alpha-toxin-induced IFN-γ, IL-17A, and IL-10 production significantly and negatively correlated with the degree of eosinophil infiltration into nasal polyps. Conversely, alpha-toxin-induced IFN-γ and IL-10 production significantly and positively correlated with FEV1/FVC. IL-10 production was significantly lower in asthmatic patients compared to non-asthmatics

CONCLUSIONS

S. aureus-derived alpha-toxin can provoke cellular responses in nasal polyps. These responses, especially failure to synthesize IL-10, may play a role in the pathophysiology of CRSwNP.

Pathogen-specific local immune fingerprints diagnose bacterial infection in peritoneal dialysis patients

Accurate and timely diagnosis of bacterial infection is crucial for effective and targeted treatment, yet routine microbiological identification is inefficient and often delayed to an extent that makes it clinically unhelpful. The immune system is capable of a rapid, sensitive and specific detection of a broad spectrum of microbes, which has been optimized over millions of years of evolution. A patient's early immune response is therefore likely to provide far better insight into the true nature and severity of microbial infections than conventional tests. To assess the diagnostic potential of pathogen-specific immune responses, we characterized the local responses of 52 adult patients during episodes of acute peritoneal dialysis (PD)-associated peritonitis by multicolor flow cytometry and multiplex ELISA, and defined the immunologic signatures in relation to standard microbiological culture results and to clinical outcomes. We provide evidence that unique local "immune fingerprints" characteristic of individual organisms are evident in PD patients on the day of presentation with acute peritonitis and discriminate between culture-negative, Gram-positive, and Gram-negative episodes of infection. Those humoral and cellular parameters with the most promise for defining disease-specific immune fingerprints include the local levels of IL-1β, IL-10, IL-22, TNF-α, and CXCL10, as well as the frequency of local γδ T cells and the relative proportion of neutrophils and monocytes/macrophages among total peritoneal cells. Our data provide proof of concept for the feasibility of using immune fingerprints to inform the design of point-of-care tests that will allow rapid and accurate infection identification and facilitate targeted antibiotic prescription and improved patient management.

Immunology of atopic eczema: overcoming the Th1/Th2 paradigm

Atopic eczema (AE) is a challenge for modern medicine, because it is prevalent, severely affects quality of life of patients and their families, and causes high socioeconomic costs. The pathogenesis of AE is complex. While initial studies suggested a Th2 deviation as primary reason for the disease, numerous studies addressed a genetically predetermined impaired epidermal barrier as leading cause in a subgroup of patients. Recently, immune changes beyond the initial Th2 concept were defined in AE, with a role for specialized dendritic cells as well as newly identified T helper cell subsets such as Th17 and Th22 cells. Furthermore, trigger factors are expanded beyond classical Th2 allergens such as pollen or house dust mites to microbial products as well as self-antigens. This review pieces together our current understanding of immune as well as barrier abnormalities into the pathogenesis mosaic of AE.

FcεRI stimulation promotes the differentiation of histamine receptor 1-expressing inflammatory macrophages

BACKGROUND

Monocyte differentiation into dendritic cells or macrophages and recruitment to peripheral organs in chronic inflammatory diseases are directed by allergen challenge via FcεRI as well as the nature of soluble factors in the microenvironment. High-affinity receptor for IgE stimulation of effector cells results in the release of histamine, which acts on various histamine receptors (HR) 1-4, expressed by immune cells.

METHODS

We examined the effect of FcεRI stimulation of human monocytes on H1R expression and function of differentiating cells. The mRNA levels of H1R, H2R and histidine decarboxylase of differentiating cells were detected by quantitative real-time PCR. Expression of CD1c, CD11c, CD68 and CD163 was detected by flow cytometry. Amount of histamine, IL-6 and IL-12p70 in the cell culture was measured with the help of cytometric bead arrays or ELISA assays. Numbers of H1R-expressing macrophages were evaluated by immunofluorescence double staining of CD68 and H1R on human skin sections.

RESULTS

We demonstrated that FcεRI stimulation promotes the generation of H1R-expressing macrophage-like cells with enhanced histamine biosynthesis and H1R-mediated proinflammatory properties. Supporting our in vitro findings, high numbers of H1R-expressing CD68(pos) macrophages were detected in the dermis of atopic dermatitis (AD) skin lesions.

CONCLUSION

Our observations point to a close histamine-/HR-mediated activation of dermal macrophages, leading to modified cell differentiation and responsiveness via H1R, which might contribute to the aggravation of allergic skin inflammation in AD.

Role of macrophages in the pathogenesis of atopic dermatitis

Atopic dermatitis (AD) is one of the most common and most intensively studied chronic inflammatory skin diseases. Several cofactors, such as an impaired skin barrier function, modifications of the immune system, and a complex genetic background, direct the course of AD. Within this complex network, macrophages play a pivotal role in enhanced susceptibility to cutaneous infections and act as central connecting components in the pathogenesis of AD on the cellular level. In AD, macrophages are known to accumulate in acutely and chronically inflamed skin. During the early and short inflammatory phase, macrophages exert proinflammatory functions like antigen-presenting phagocytosis and the production of inflammatory cytokines and growth factors that facilitate the resolution of inflammation. However, persistence of pro-inflammatory activity and altered function of macrophages result in the development of chronic inflammatory diseases such as AD. The exact mechanism of macrophages activation in these processes is not yet completely understood. Further studies should be performed to clarify the dysregulated mechanism of macrophages activation in AD, and this would allow us to target these cells with versatile functions for therapeutic purpose and improve and control the disease. In this paper, we highlight the new findings on dysregulated function of macrophages and the importance of these cells in the pathogenesis of AD in general and the contribution of these cells in enhanced susceptibility against microbial infections in particular.