Neutrophil extracellular traps enhance S. aureus skin colonization by oxidative stress induction and downregulation of epidermal barrier genes

Neutrophil Extracellular Traps Drive Kidney Stone Formation

Introduction

This study aims to explore the contribution of neutrophil extracellular traps (NETs) to kidney stones.

Methods

The microarray data from GSE73680 and bioinformatic analysis were applied to identify differentially expressed genes in patients with kidney stones. A rat model of kidney stones was established through ethylene glycol and ammonium chloride administration. The plasma was collected for examining cf-DNA, DNase I, MPO-DNA, H3Cit and NE. Superoxide dismutase, malondialdehyde, creatinine, blood urea nitrogen, and calcium were examined through biochemical analysis. MPO, H3Cit, and NE in kidney tissues were detected via immunofluorescence staining. Cell apoptosis was evaluated through TUNEL assays. HE, Periodic Acid-Schiff and Von Kossa staining were applied to determine histological structure, calcium deposits and stone formation in the kidneys. Neutrophil elastase inhibitor Sivelestat (SIVE) was administrated for NET suppression in rats.

Results

A total of 403 differentially expressed genes including 270 upregulated and 133 downregulated genes were identified between renal papillary tissues with Randall's plaque and normal tissues. Gene ontology enrichment, KEGG pathway and protein-protein interaction network analysis of these dysregulated genes were performed. Moreover, increased NET markers including cf-DNA, DNase I, MPO-DNA, H3Cit and NE and calcium deposits were observed in patients with kidney stones. Subsequently, we established a rat model of kidney stones. We found that NET formation was significantly elevated in kidney stone rats, and renal tubular injury and apoptotic cells were enhanced as kidney stones developed. Strikingly, we found that suppression of NETs via SIVE could significantly reduce calcium deposits and apoptotic cells and alleviate tubular injury, thus improving kidney function.

Conclusion

NETs drive the formation of kidney stones, thus aggravating kidney injury. Our study identifies NETs as a potential diagnostic and therapeutic biomarker for nephrolithiasis.

Neutrophils in Atopic Dermatitis

Neutrophils have a critical role in inflammation. Recent studies have identified their distinctive presence in certain types of atopic dermatitis (AD), yet their exact function remains unclear. This review aims to compile studies elucidating the role of neutrophils in AD pathophysiology. Proteins released by neutrophils, including myeloperoxidase, elastase, and lipocalin, contribute to pruritus progression in AD. Neutrophilic oxidative stress and the formation of neutrophil extracellular traps may further worsen AD. Elevated neutrophil elastase and high-mobility group box 1 protein expression in AD patients' skin exacerbates epidermal barrier defects. Neutrophil-mast cell interactions in allergic inflammation steer the immunological response toward Th2 imbalance and activate the Th17 pathway, particularly in response to allergens or infections linked to AD. Notably, drugs alleviating pruritic symptoms in AD inhibit neutrophilic inflammation. In conclusion, these findings underscore that neutrophils may be therapeutic targets for AD symptoms, emphasizing their inclusion in AD treatment strategies.

Microenvironmental host-microbe interactions in chronic inflammatory skin diseases

Several microbiome studies have recently demonstrated microbial dysbiosis in various chronic inflammatory skin diseases, and it is considered an important role in the pathogenesis. Although the role of skin dysbiosis in inflammatory skin diseases is debatable, the local microenvironment is considered essential concerning compositional changes and functional alterations of the skin microbiota. Indeed, various local nutrients (e.g., lipids), pH values, water, oxygen, and antimicrobial peptides may affect the level of skin dysbiosis in these skin diseases. In particular, in atopic dermatitis and hidradenitis suppurativa, significant changes in skin dysbiosis have been associated with local aberrant host immune changes. In this review, the potential pathogenic crosstalk between the host and the microbiota is reviewed in relation to the physical, chemical, and biological microenvironments of various chronic inflammatory skin diseases.

Effects of Huang-Lian-Jie-Du decoction on improving skin barrier function and modulating T helper cell differentiation in 1-chloro-2,4-dinitrobenzene-induced atopic dermatitis mice

Background: Atopic dermatitis (AD) is among the most frequently encountered skin diseases, bothering a considerable number of patients. Today, corticosteroids and antihistamines are among the numerous drugs applied for the therapy of AD. However, lengthy use of them contributes to side effects, such as physiological changes in skin. As an alternative and supplementary therapy, traditional Chinese medicine has become a trend for AD treatment. Huang-Lian-Jie-Du decoction (HLJDD), a renowned herbal formula has been employed to treat inflammatory diseases such as AD. However, its role in regulating immunity in AD remains unclear. The object of this study was to elucidate the efficacy of HLJDD and reveal the implicit mechanism from an immunological perspective in AD-like mice. Methods: In brief, 1-chloro-2,4-dinitrobenzene (DNCB) for the sensitization phase (1% DNCB) and stimulation phase (1.5% DNCB) were applied for BALB/c mice. HLJDD and dexamethasone (DXMS) were administered orally to the mice. Mice skin and spleens were collected to evaluate the efficacy of HLJDD. 16S rRNA sequencing was applied to evaluate the commensal microbiota changes in skin and fecal. In vitro, spleen CD4+ T cells and bone marrow-derived mast cells (BMMCs) were co-cultured to explore the modulation of HLJDD in T helper (Th) cells phenotyping. Results: HLJDD showcased a substantial amelioration in skin through the upregulation of FLG, LOR, AQP3, and reducing scratching behaviors in AD-like mice, Also, the quantity of infiltrated mast cells (MCs), pruritus-related mRNA were decreased. In addition, the expression of OX40/OX40L was decreased by HLJDD, which was critical in Th-cell phenotyping. With the treatment of HLJDD, Th1/Th2 and Th17/Treg ratios in AD-like mice became balanced. The structure of commensal microbiota in AD-like mice was affected by HLJDD. HLJDD could also improve the imbalance of Th17/Treg in vitro. Conclusion: HLJDD could improve the symptoms of AD-like mice by alleviating the scratching behaviors via decreased Th2 and pruritus-related mRNA expression. HLJDD also enhanced the relative diversity of skin microbiota and changed the structure of intestinal microbiota. An in-depth study found that HLJDD could balance the ratio of Th1/Th2, Th17/Treg in AD-like mice, and Th17/Treg in vitro by regulating the OX40/OX40L signaling pathway.

Atopic dermatitis and IgE-mediated food allergy: Common biologic targets for therapy and prevention

OBJECTIVE

To highlight common mechanistic targets for the treatment of atopic dermatitis (AD) and IgE-mediated food allergy (IgE-FA) with potential to be effective for both diseases and prevent atopic progression.

DATA SOURCES

Data sources were PubMed searches or National Clinical Trials (NCT)-registered clinical trials related to AD, IgE-FA, and other atopic conditions, especially focused on the pediatric population.

STUDY SELECTIONS

Human seminal studies and/or articles published in the past decade were emphasized with reference to preclinical models when relevant. NCT-registered clinical trials were filtered by inclusion of pediatric subjects younger than 18 years with special focus on children younger than 12 years as a critical period when AD and IgE-FA diseases may often be concurrent.

RESULTS

AD and IgE-FA share several pathophysiologic features, including epithelial barrier dysfunction, innate and adaptive immune abnormalities, and microbial dysbiosis, which may be critical for the clinical progression between these diseases. Revolutionary advances in targeted biologic therapies have shown the benefit of inhibiting type 2 immune responses, using dupilumab (anti-interleukin-4Rα) or omalizumab (anti-IgE), to potentially reduce symptom burden for both diseases in pediatric populations. Although the potential for biologics to promote disease remission (AD) or sustained unresponsiveness (IgE-FA) remains unclear, the refinement of biomarkers to predict infants at risk for atopic disorders provides promise for prevention through timely intervention.

CONCLUSION

AD and IgE-FA exhibit common features that may be leveraged to develop biologic therapeutic strategies to treat both conditions and even prevent atopic progression. Future studies should be designed with consistent age stratification in the pediatric population and standardized regimens of adjuvant oral immunotherapy or dose escalation (IgE-FA) to improve cross-study interpretation.

Commensal microbe regulation of skin cells in disease

Human skin is the host to various commensal microbes that constitute a substantial microbial community. The reciprocal communication between these microbial inhabitants and host cells upholds both the morphological and functional attributes of the skin layers, contributing indispensably to microenvironmental and tissue homeostasis. Thus, disruption of the skin barrier or imbalances in the microbial communities can exert profound effects on the behavior of host cells. This influence, mediated by the microbes themselves or their metabolites, manifests in diverse outcomes. In this review, we examine existing knowledge to provide insight into the nuanced behavior exhibited by the microbiota on skin cells in health and disease states. These interactions provide insight into potential cellular targets for future microbiota-based therapies to prevent and treat skin disease.

Eosinophil extracellular vesicles and DNA traps in allergic inflammation

Eosinophil granulocytes, a specialized subset of white blood cells, have traditionally been associated with allergic responses and parasitic infections. However, recent research has unveiled their versatile roles in immune regulation beyond these classical functions. This review highlights the emerging field of eosinophil biology, with a particular focus on their release of extracellular vesicles (EVs) and extracellular DNA traps (EETs). It further explores potential implications of eosinophil-derived EVs and EETs for immune responses during inflammatory diseases. The release of EVs/EETs from eosinophils, which also affects the eosinophils themselves, may influence both local and systemic immune reactions, affecting the pathophysiology of conditions such as airway inflammation, chronic rhinosinusitis and atopic dermatitis.

Lipase-mediated detoxification of host-derived antimicrobial fatty acids by Staphylococcus aureus

Long-chain fatty acids with antimicrobial properties are abundant on the skin and mucosal surfaces, where they are essential to restrict the proliferation of opportunistic pathogens such as Staphylococcus aureus. These antimicrobial fatty acids (AFAs) elicit bacterial adaptation strategies, which have yet to be fully elucidated. Characterizing the pervasive mechanisms used by S. aureus to resist AFAs could open new avenues to prevent pathogen colonization. Here, we identify the S. aureus lipase Lip2 as a novel resistance factor against AFAs. Lip2 detoxifies AFAs via esterification with cholesterol. This is reminiscent of the activity of the fatty acid-modifying enzyme (FAME), whose identity has remained elusive for over three decades. In vitro, Lip2-dependent AFA-detoxification was apparent during planktonic growth and biofilm formation. Our genomic analysis revealed that prophage-mediated inactivation of Lip2 was rare in blood, nose, and skin strains, suggesting a particularly important role of Lip2 for host - microbe interactions. In a mouse model of S. aureus skin colonization, bacteria were protected from sapienic acid (a human-specific AFA) in a cholesterol- and lipase-dependent manner. These results suggest Lip2 is the long-sought FAME that exquisitely manipulates environmental lipids to promote bacterial growth in otherwise inhospitable niches.

Crosstalk between keratinocytes and neutrophils shapes skin immunity against S. aureus infection

Introduction

Staphylococcus aureus (S. aureus) infection of the skin leads to a rapid initial innate immune response with keratinocytes in the epidermis as the initial sensors. Polymorphonuclear neutrophils (PMNs) are the first innate immune cells to infiltrate infection sites where they provide an effective first-line of defense. Previous work of our group showed that in inflamed skin a crosstalk between PMNs and keratinocytes results in enhanced S. aureus skin colonization.

Methods

In this work, we used an in vitro co-culture model to studied the crosstalk between primary human keratinocytes (PHKs) and PMNs in a sterile environment and upon S. aureus infection. We investigated the influence of PHKs on PMN activation by analyzing PMN lifespan, expression of degranulation markers and induction of proinflammatory cytokines. Furthermore, we analyzed the influence of PMNs on the inflammatory response of PHKs. Finally, we investigated the influence of the skin microbiome on PMN-mediated skin inflammation.

Results

We show that co-culture of PMNs with PHKs induces activation and degranulation of PMNs and significantly enhances their lifespan compared to PMN cultivation alone by an IL-8 mediated mechanism and, furthermore, primes PMNs for enhanced activity after S. aureus infection. The prolonged incubation with PMNs also induces inflammatory responses in PHKs which are further exacerbated in the presence of S. aureus and induces further PMN recruitment thus fueling skin inflammation. Interestingly, infection of PHKs with the skin commensal S. epidermidis reduces the inflammatory effects of PMNs in the skin and exhibits an anti-inflammatory effect.

Discussion

Our data indicate that skin infiltrating PMNs and PHKs influence each other in such a way to enhance skin inflammation and that commensal bacteria are able to reduce the inflammatory effect.