interleukin-8 and Staphylococcal-Skin-Infections

Staphylococcus aureus is a leading cause of skin and soft issue infection, but paradoxically, it also transiently, and often harmlessly, colonizes human skin. An obstacle to understanding this contradiction has been a shortage of in vivo models reproducing the unique structure and immunology of human skin. In this work, we developed a humanized model to study how healthy adult human skin responds to colonizing methicillin-resistant S. aureus (MRSA). We demonstrate the importance of the outer stratum corneum as the major site of bacterial colonization and how noninvasive MRSA adhesion to corneocytes induces a local inflammatory response in underlying skin layers. This signaling recruits neutrophils to the skin, where they control bacterial numbers, mediating transiency in colonization. This work highlights the spatiotemporal aspects of human skin colonization and demonstrates a subclinical inflammatory response to noninvasive MRSA that allows human skin to regulate the bacterial population at its outer surface.

Topics: Animals; Colony Count, Microbial; Dermis; Epidermis; Female; Heterografts; Humans; Inflammation; Interleukin-8; Male; Methicillin-Resistant Staphylococcus aureus; Mice, SCID; Models, Biological; Neutrophil Infiltration; Skin; Staphylococcal Skin Infections; Up-Regulation

Resistance to bacterial skin infections, for example with Staphylococcus aureus (S. aureus), is based on the function of intact innate immune mechanisms. Toll-like receptor (TLR)-2 recognizes components of S. aureus and is known to be expressed on monocytes. Staphylococcal exotoxins such as staphylococcal enterotoxin B (SEB) or α-toxin are produced by many S. aureus strains. To investigate TLR-2 regulation and function on human monocytes upon stimulation with staphylococcal exotoxins to elucidate a putative feedback loop between different staphylococcal components. Monocytes were stimulated with α-toxin or SEB, respectively. TLR-2 expression and regulation as well as functional effects of TLR-2 stimulation with Pam3Cys (TLR-2/TLR-1), lipoteichoic acid (LTA) (TLR-2/TLR-6) and peptidoglycan (PGN) (TLR-2 and Nod) were then investigated both at the mRNA and protein level and compared to monocytes from patients with psoriasis. α-toxin significantly upregulated TLR-2 expression. TLR-2 mediated IL-1β, IL-6 and IL-8 secretion was significantly augmented after upregulation with staphylococcal exotoxins. CD36 expression was significantly more downregulated after TLR-2 upregulation with SEB and consecutive LTA stimulation and TLR-2 upregulation with α-toxin following LTA and PGN stimulation, respectively. PGN enhanced CD54 expression after upregulation of the receptor with α-toxin. Expression of HLA-DR was unaffected. However, no differences were observed in monocytes from psoriasis patients compared to healthy controls. Together, our findings provide a new link between staphylococcal α-toxin and TLR-2 signalling in monocytes which may have implications for skin diseases where skin colonization with S. aureus and dysregulation of TLR-2 have been described.

Topics: Bacterial Toxins; CD36 Antigens; Enterotoxins; Hemolysin Proteins; Humans; Immunity, Innate; In Vitro Techniques; Interleukin-1beta; Interleukin-6; Interleukin-8; Monocytes; RNA, Messenger; Signal Transduction; Staphylococcal Skin Infections; Staphylococcus aureus; Toll-Like Receptor 2; Up-Regulation

A number of studies argue in favour of an important role of microbial colonization, in particular of Staphylococcus aureus, in triggering atopic dermatitis (AD) flare-up and psoriasis, in particular through the superantigenic properties of toxins generated by S. aureus.. The aim of this study was to assess the efficacy of a 3-week Avène hydrotherapy on the skin surface of patients suffering from psoriasis or atopic dermatitis.. Skin samples were taken from healthy subjects or atopic (n = 18) or psoriatic patients (n = 39) undergoing hydrotherapy at Avène at the beginning (D0) and the end of treatment (D18). The severity of the dermatosis was evaluated according to SCORing Atopic Dermatitis (SCORAD) or Psoriasis Area Severity Index (PASI) scores at D0 and D18. Marker of inflammation interleukin 8 (IL-8), S. aureus colonization (protein A) and enterotoxins were assessed in skin samples using RT-PCR.. At D0, significant differences were observed between healthy subjects and atopic or psoriatic patients in all the parameters evaluated (IL-8, protein A). At the end of the hydrotherapy, a significant decrease in SCORAD was associated with a significant reduction of IL-8, S. aureus colonization and enterotoxin D in patients with atopic dermatitis. Similarly, a significant decrease in PASI was associated with a significant reduction of IL-8, S. aureus colonization and enterotoxin N in patients with psoriasis.. This study demonstrates the positive effects of Avène hydrotherapy on the skin of patients suffering from chronic dermatosis, with decreased inflammation and reduced colonization by S. aureus.

Topics: Adult; Child; Child, Preschool; Dermatitis, Atopic; Enterotoxins; Humans; Hydrotherapy; Infant; Interleukin-8; Mineral Waters; Psoriasis; Severity of Illness Index; Staphylococcal Protein A; Staphylococcal Skin Infections; Staphylococcus aureus; Statistics, Nonparametric; Treatment Outcome; Young Adult

Bacterial infection with Staphylococcus aureus is a known trigger for worsening of atopic dermatitis (AD); the exact mechanisms by which bacterial infection worsens dermatitis are unknown.. We sought to characterize the amounts of the biologically active bacterial lipoprotein lipoteichoic acid (LTA) in infected AD lesions.. Eighty-nine children with clinically impetiginized lesions of AD were enrolled in this study. A lesion was graded clinically by using the Eczema Area and Severity Index (EASI), wash fluid obtained from the lesion for quantitative bacterial culture, and measurement of LTA and cytokines. The staphylococcal isolate was tested for antibiotic susceptibilities. The patients were treated with a regimen that included topical corticosteroids and systemic antibiotics, and the lesion was reanalyzed after 2 weeks.. S aureus was identified in 79 of 89 children enrolled in the study. The bacterial colony-forming unit (CFU) counts correlated with the EASI lesional score (P = .04). LTA levels as high as 9.8 mug/mL were measured in the wash fluid samples, and the amounts correlated with the lesional EASI scores (P = .01) and S aureus CFU (P < .001). Approximately 30% of clinically impetiginized AD lesions contained greater than 1 mug/mL LTA, amounts that exert effects on various cell types in vitro. Moreover, injection of skin tissue ex vivo with amounts of LTA found in AD lesions resulted in epidermal cytokine gene expression.. Pharmacologic levels of LTA are found in many infected atopic dermatitis lesions.

Topics: Child; Child, Preschool; Colony Count, Microbial; Dermatitis, Atopic; Eczema; Humans; Infant; Interleukin-8; Lipopolysaccharides; Severity of Illness Index; Skin; Staphylococcal Skin Infections; Staphylococcus aureus; Teichoic Acids; Tumor Necrosis Factor-alpha

Staphylococcus aureus is a significant human pathogen that can colonize the skin. Neutrophils are well known to be involved in clearance of the bacterium. This study focused on exploring the role that human keratinocytes have as first responders to bacterial challenges. IL-1alpha and IL-1beta increased mRNA production and protein secretion of the neutrophil chemotactic CXCL1, CXCL2, and IL-8 in keratinocytes. S. aureus and the bacterial cell wall components lipoteichoic acid (LTA) and peptidoglycan (PGN) induced similar expression profiles in a Toll-like receptor (TLR)-2-dependent manner. Interestingly, the S. aureus-induced mRNA levels peaked at later time points than those induced by IL-1. The S. aureus-activated chemokine production was preceded by significant IL-1alpha and IL-1beta secretion. Expression of IL-1alpha was significantly higher than that of IL-1beta. Inhibition of IL-1RI using neutralizing antibodies revealed that S. aureus-derived LTA and PGN-induced chemokine expression requires IL-1RI engagement. Surprisingly, we further found that chemokine secretion is dependent upon endocrine IL-1alpha, but not IL-1beta, signaling. Our data show that the innate immune response of keratinocytes is regulated differently than those of other cell types. This may represent a fail-safe system that protects the host against genetic variation and immune evasion mechanisms developed by pathogens.

Topics: Antibodies, Neutralizing; Autocrine Communication; Cell Wall; Cells, Cultured; Chemokine CXCL1; Chemokine CXCL2; Chemotaxis, Leukocyte; Humans; Interleukin-1alpha; Interleukin-1beta; Interleukin-8; Keratinocytes; Lipopolysaccharides; Neutrophils; Oligonucleotide Array Sequence Analysis; Peptidoglycan; Receptors, Interleukin-1; RNA, Messenger; Signal Transduction; Staphylococcal Skin Infections; Staphylococcus aureus; Teichoic Acids; Toll-Like Receptor 2

The human epidermis provides a first line of defense against exogenous pathogens. Resistance to bacterial skin infections, e.g. with Staphylococcus aureus (S. aureus), is based on the function of intact innate immune mechanisms in the epidermis, mainly provided by keratinocytes. They establish the local cytokine and chemokine milieu which is necessary for attracting other cells participating in an immune response. Toll-like receptor (TLR)-2 recognizes components of S. aureus and is known to be expressed on keratinocytes. The aim of this study was to investigate TLR-2-mediated chemokine and cytokine secretion on human primary keratinocytes (HPKs) both on mRNA and on protein level. As there is no selective TLR-2 ligand known so far, we chose Pam3Cys that acts via TLR-2/TLR-1 heterodimers, lipoteichoic acid (LTA) that acts via TLR-2/TLR-6 and peptidoglycan (PGN) which acts via TLR-2 and Nod. Pam3Cys stimulation yielded in an enhanced secretion of CCL20, CCL2, MMP9 and IL-8 in HPK, whereas stimulation with PGN or LTA showed no or solely slight effects. Our findings show evidence for a functional TLR-2/TLR-1 signalling profile in HPKs upon stimulation with Pam3Cys contributing to the defense against bacterial skin infections.

Topics: Cells, Cultured; Chemokine CCL2; Chemokine CCL20; Chemokines; Epidermal Cells; Humans; Interleukin-8; Keratinocytes; Ligands; Lipoproteins; Matrix Metalloproteinase 9; RNA, Messenger; Staphylococcal Skin Infections; Toll-Like Receptor 1; Toll-Like Receptor 2; Toll-Like Receptor 6

Hyper-IgE syndrome (HIES) is a primary immunodeficiency characterized by atopic manifestations and susceptibility to infections with extracellular pathogens, typically Staphylococcus aureus, which preferentially affect the skin and lung. Previous studies reported the defective differentiation of T helper 17 (Th17) cells in HIES patients caused by hypomorphic STAT3 mutations. However, the apparent contradiction between the systemic Th17 deficiency and the skin/lung-restricted susceptibility to staphylococcal infections remains puzzling. We present a possible molecular explanation for this enigmatic contradiction. HIES T cells showed impaired production of Th17 cytokines but normal production of classical proinflammatory cytokines including interleukin 1beta. Normal human keratinocytes and bronchial epithelial cells were deeply dependent on the synergistic action of Th17 cytokines and classical proinflammatory cytokines for their production of antistaphylococcal factors, including neutrophil-recruiting chemokines and antimicrobial peptides. In contrast, other cell types were efficiently stimulated with the classical proinflammatory cytokines alone to produce such factors. Accordingly, keratinocytes and bronchial epithelial cells, unlike other cell types, failed to produce antistaphylococcal factors in response to HIES T cell-derived cytokines. These results appear to explain, at least in part, why HIES patients suffer from recurrent staphylococcal infections confined to the skin and lung in contrast to more systemic infections in neutrophil-deficient patients.

Topics: Animals; Antigens, Bacterial; Antigens, Fungal; beta-Defensins; Chemokines; Cytokines; Epithelial Cells; Humans; Interleukin-8; Job Syndrome; Keratinocytes; Lung Diseases; Receptors, Interleukin-1; Respiratory Mucosa; Staphylococcal Infections; Staphylococcal Skin Infections; STAT3 Transcription Factor; T-Lymphocytes, Helper-Inducer