Clonal Vγ6+Vδ4+ T cells promote IL-17-mediated immunity against Staphylococcus aureus skin infection.

T cell cytokines contribute to immunity against Staphylococcus aureus, but the predominant T cell subsets involved are unclear. In an S. aureus skin infection mouse model, we found that the IL-17 response was mediated by γδ T cells, which trafficked from lymph nodes to the infected skin to induce neutrophil recruitment, proinflammatory cytokines IL-1α, IL-1ß, and TNF, and host defense peptides. RNA-seq for TRG and TRD sequences in lymph nodes and skin revealed a single clonotypic expansion of the encoded complementarity-determining region 3 amino acid sequence, which could be generated by canonical nucleotide sequences of TRGV5 or TRGV6 and TRDV4 However, only TRGV6 and TRDV4 but not TRGV5 sequences expanded. Finally, Vγ6+ T cells were a predominant γδ T cell subset that produced IL-17A as well as IL-22, TNF, and IFNγ, indicating a broad and substantial role for clonal Vγ6+Vδ4+ T cells in immunity against S. aureus skin infections.

Injury, dysbiosis, and filaggrin deficiency drive skin inflammation through keratinocyte IL-1α release.

BACKGROUND: Atopic dermatitis (AD) is associated with epidermal barrier defects, dysbiosis, and skin injury caused by scratching. In particular, the barrier-defective epidermis in patients with AD with loss-of-function filaggrin mutations has increased IL-1α and IL-1ß levels, but the mechanisms by which IL-1α, IL-1ß, or both are induced and whether they contribute to the aberrant skin inflammation in patients with AD is unknown. OBJECTIVE: We sought to determine the mechanisms through which skin injury, dysbiosis, and increased epidermal IL-1α and IL-1ß levels contribute to development of skin inflammation in a mouse model of injury-induced skin inflammation in filaggrin-deficient mice without the matted mutation (ft/ft mice). METHODS: Skin injury of wild-type, ft/ft, and myeloid differentiation primary response gene-88-deficient ft/ft mice was performed, and ensuing skin inflammation was evaluated by using digital photography, histologic analysis, and flow cytometry. IL-1α and IL-1ß protein expression was measured by means of ELISA and visualized by using immunofluorescence and immunoelectron microscopy. Composition of the skin microbiome was determined by using 16S rDNA sequencing. RESULTS: Skin injury of ft/ft mice induced chronic skin inflammation involving dysbiosis-driven intracellular IL-1α release from keratinocytes. IL-1α was necessary and sufficient for skin inflammation in vivo and secreted from keratinocytes by various stimuli in vitro. Topical antibiotics or cohousing of ft/ft mice with unaffected wild-type mice to alter or intermix skin microbiota, respectively, resolved the skin inflammation and restored keratinocyte intracellular IL-1α localization. CONCLUSIONS: Taken together, skin injury, dysbiosis, and filaggrin deficiency triggered keratinocyte intracellular IL-1α release that was sufficient to drive chronic skin inflammation, which has implications for AD pathogenesis and potential therapeutic targets.

Emerging Nonsteroid-Based Procedural Therapies for Alopecia Areata: A Systematic Review.

BACKGROUND: Alopecia areata (AA) is a common form of patchy, nonscarring hair loss. Although intralesional steroid injections are currently the mainstay procedural therapy for AA, other nonsteroid-based procedural therapies, including platelet-rich plasma (PRP), ultraviolet radiation (UVR), and laser-based modalities, are emerging as practical options. OBJECTIVE: To systematically review nonsteroid-based procedural therapies for AA and recapitulate the available clinical data. MATERIALS AND METHODS: A systematic review of the literature was performed searching PubMed/MEDLINE databases identifying studies investigating PRP, UVR, and laser-based modalities for AA treatment. RESULTS: Literature search yielded 644 articles encompassing PRP, UVR, and laser treatment modalities for AA. Of the 644 articles, 46 met inclusion criteria. Although numerous reports demonstrate strong potential for PRP, UVR, and laser modalities in treating AA, high-quality evidence supporting their efficacy is still lacking. CONCLUSION: There is an abundance of evidence for nonsteroid-based procedural therapies in the treatment of AA. Randomized control trials comparing these treatment options head-to-head should be performed to better understand the true efficacy of these treatments.

Neutralizing Alpha-Toxin Accelerates Healing of Staphylococcus aureus-Infected Wounds in Nondiabetic and Diabetic Mice.

Staphylococcus aureus wound infections delay healing and result in invasive complications such as osteomyelitis, especially in the setting of diabetic foot ulcers. In preclinical animal models of S. aureus skin infection, antibody neutralization of alpha-toxin (AT), an S. aureus-secreted pore-forming cytolytic toxin, reduces disease severity by inhibiting skin necrosis and restoring effective host immune responses. However, whether therapeutic neutralization of alpha-toxin is effective against S. aureus-infected wounds is unclear. Herein, the efficacy of prophylactic treatment with a human neutralizing anti-AT monoclonal antibody (MAb) was evaluated in an S. aureus skin wound infection model in nondiabetic and diabetic mice. In both nondiabetic and diabetic mice, anti-AT MAb treatment decreased wound size and bacterial burden and enhanced reepithelialization and wound resolution compared to control MAb treatment. Anti-AT MAb had distinctive effects on the host immune response, including decreased neutrophil and increased monocyte and macrophage infiltrates in nondiabetic mice and decreased neutrophil extracellular traps (NETs) in diabetic mice. Similar therapeutic efficacy was achieved with an active vaccine targeting AT. Taken together, neutralization of AT had a therapeutic effect against S. aureus-infected wounds in both nondiabetic and diabetic mice that was associated with differential effects on the host immune response.

Pembrolizumab-Induced Lichen Planus Pemphigoides in a Patient with Metastatic Adrenocortical Cancer: A Case Report and Literature Review.

While the advent of immune-checkpoint inhibitors has revolutionized cancer therapy, immune-related adverse effects (irAEs) have also been on the rise. Cutaneous toxicities are among the most common irAEs, especially in the context of programmed cell death protein-1 (PD-1) inhibitors like pembrolizumab. Herein, we report a case of anti-PD-1-induced lichen planus pemphigoides (LPP)-a rare autoimmune blistering disorder with characteristics of both lichen planus and bullous pemphigoid. To our knowledge, this is the first reported case of LPP following anti-PD-1 therapy for metastatic adrenocortical cancer. Recognizing that LPP is within the spectrum of irAEs is important, especially as the indications for immunotherapy grow to include rarer malignancies like adrenocortical cancer. In addition to our case presentation, we also provide a comprehensive review of the literature surrounding immunotherapy-induced LPP-highlighting key characteristics towards the early recognition and clinical management of this cutaneous irAE.

Mast Cell Stabilizers in the Treatment of Rosacea: A Review of Existing and Emerging Therapies.

Rosacea is a chronic inflammatory skin disease characterized by centrofacial erythema, papules, pustules, and telangiectasias. The onset of rosacea typically occurs after 30 years of age. It is estimated that approximately 2-5% of adults worldwide are affected. While the exact etiology of rosacea remains unknown, its pathogenesis is thought to be multifactorial with both environmental and genetic factors implicated. Ultraviolet radiation, heat, steam, ingested agents, including spicy foods and alcohol, host vasculature, dermal matrix degeneration, genetic susceptibility, and microbial organisms, including Demodex mites and Heliobacter pylori, have been implicated in the development of rosacea. Recently, mast cells (MCs) have emerged as key players in the pathogenesis of rosacea through the release of pro-inflammatory cytokines, chemokines, proteases, and antimicrobial peptides leading to cutaneous vasodilation, angiogenesis, and tissue fibrosis. Several existing and emerging topical, oral, and injectable therapeutics have been associated with improvement of rosacea symptoms based on their ability to stabilize and downregulate activated MCs. Herein, we review the data implicating MCs in the pathogenesis of rosacea and discuss interventions that may stabilize this pathway.

Rosacea and Associated Comorbidities: A Google Search Trends Analysis.

BACKGROUND: There is recent evidence linking rosacea to systemic disease. OBJECTIVE: We sought to identify correlations in Google searches (Google LLC, Mountain View, California) for rosacea and comorbid conditions to assess whether the public is seeking information regarding these trends. METHODS: Google search data from January 1, 2004, to February 28, 2018, for rosacea and search terms representing common comorbid conditions were investigated. This analysis included searches occurring in the United States (US), Canada, the United Kingdom (UK), and Australia. Search volume index (SVI) data were plotted over time and Pearson correlation coefficients were calculated from search data to assess for correlations between search terms. RESULTS: The level of interest in rosacea was highest in the spring and lowest in the winter in the US, Canada, and UK. Seasonal search trends in Australia were the inverse of those in northern hemisphere nations. Significant correlations were found between depression and rosacea SVI in the US (R=0.481; p<0.001), dementia and rosacea SVI in the UK (R=0.774; p=0.011), and hypothyroidism and rosacea SVI (R=0.752; p<0.001) in the UK. Additionally, search trends for irritable bowel syndrome (R=0.399; p<0.001) and ulcerative colitis (R=0.514; p=0.032) correlated significantly with rosacea in Canada and the UK, respectively. In Australia, search trends for osteoporosis significantly correlated with rosacea (R=0.394; p<0.001). CONCLUSIONS: Our findings indicate growing interest among the general public regarding rosacea and comorbid diseases, which behooves clinicians to adopt a more comprehensive approach in managing rosacea patients.

Evaluation of Physiological, Psychological, and Lifestyle Factors Associated with Premature Hair Graying.

BACKGROUND: Canities, or hair graying, is believed to be driven by the cytotoxic effect of reactive oxygen species on follicular melanocytes, thus raising the concern that premature hair graying (PHG) may represent an outward sign of systemic oxidative stress. OBJECTIVE: This study aimed to identify the physiological, psychological, and lifestyle factors associated with PHG (defined as graying at age ≤30 years) in men and women. MATERIALS AND METHODS: Data from 467 participants (female = 354 and male = 113; age: 18-77 years) were collected and analyzed, including demographic information, medical history, family history, supplement intake, and lifestyle factors. RESULTS: PHG was found to be significantly associated with a history of PHG in the mother, P<0.001, odds ratio (OR) = 3.165; father, P<0.001, OR = 5.166; maternal grandparent, P= 0.002, OR = 2.442; paternal grandparent, P= 0.007, OR = 2.369; and siblings, P<0.001, OR = 3.125. PHG was significantly associated with iron deficiency (P = 0.026, OR = 1.751) and family history of depression (P = 0.012, OR = 1.603), while herpes simplex virus infection (P = 0.004, OR = 0.367) and smoking history (P = 0.003) demonstrated significant negative associations. In Caucasians only (n = 306), in addition to these trends, irritable bowel syndrome was also significantly associated with PHG (P = 0.010, OR = 2.753). In Asians only (n = 75), history of heart disease in a first-degree relative (P = 0.038) was significantly associated with PHG. LIMITATIONS: As a survey study, the findings may be subject to recall bias. CONCLUSIONS: Important associations exist between PHG and family history of PHG, psychiatric history, supplement use, and vitamin deficiencies, providing insight into the pathophysiology and potential comorbidities of PHG.

In Vivo Bioluminescence Imaging in a Rabbit Model of Orthopaedic Implant-Associated Infection to Monitor Efficacy of an Antibiotic-Releasing Coating.

BACKGROUND: In vivo bioluminescence imaging (BLI) provides noninvasive monitoring of bacterial burden in animal models of orthopaedic implant-associated infection (OIAI). However, technical limitations have limited its use to mouse and rat models of OIAI. The goal of this study was to develop a larger, rabbit model of OIAI using in vivo BLI to evaluate the efficacy of an antibiotic-releasing implant coating. METHODS: A nanofiber coating loaded with or without linezolid-rifampin was electrospun onto a surgical-grade locking peg. To model OIAI in rabbits, a medial parapatellar arthrotomy was performed to ream the femoral canal, and a bright bioluminescent methicillin-resistant Staphylococcus aureus (MRSA) strain was inoculated into the canal, followed by retrograde insertion of the coated implant flush with the articular surface. In vivo BLI signals were confirmed by ex vivo colony-forming units (CFUs) from tissue, bone, and implant specimens. RESULTS: In this rabbit model of OIAI (n = 6 rabbits per group), implants coated without antibiotics were associated with significantly increased knee width and in vivo BLI signals compared with implants coated with linezolid-rifampin (p < 0.001 and p < 0.05, respectively). On day 7, the implants without antibiotics were associated with significantly increased CFUs from tissue (mean [and standard error of the mean], 1.4 × 10 ± 2.1 × 10 CFUs; p < 0.001), bone (6.9 × 10 ± 3.1 × 10 CFUs; p < 0.05), and implant (5.1 × 10 ± 2.2 × 10 CFUs; p < 0.05) specimens compared with implants with linezolid-rifampin, which demonstrated no detectable CFUs from any source. CONCLUSIONS: By combining a bright bioluminescent MRSA strain with modified techniques, in vivo BLI in a rabbit model of OIAI demonstrated the efficacy of an antibiotic-releasing coating. CLINICAL RELEVANCE: The new capability of in vivo BLI for noninvasive monitoring of bacterial burden in larger-animal models of OIAI may have important preclinical relevance.

Clonally expanded γδ T cells protect against Staphylococcus aureus skin reinfection.

The mechanisms that mediate durable protection against Staphylococcus aureus skin reinfections are unclear, as recurrences are common despite high antibody titers and memory T cells. Here, we developed a mouse model of S. aureus skin reinfection to investigate protective memory responses. In contrast with WT mice, IL-1ß-deficient mice exhibited poor neutrophil recruitment and bacterial clearance during primary infection that was rescued during secondary S. aureus challenge. The γδ T cells from skin-draining LNs utilized compensatory T cell-intrinsic TLR2/MyD88 signaling to mediate rescue by trafficking and producing TNF and IFN-γ, which restored neutrophil recruitment and promoted bacterial clearance. RNA-sequencing (RNA-seq) of the LNs revealed a clonotypic S. aureus-induced γδ T cell expansion with a complementarity-determining region 3 (CDR3) aa sequence identical to that of invariant Vγ5+ dendritic epidermal T cells. However, this T cell receptor γ (TRG) aa sequence of the dominant CDR3 sequence was generated from multiple gene rearrangements of TRGV5 and TRGV6, indicating clonotypic expansion. TNF- and IFN-γ-producing γδ T cells were also expanded in peripheral blood of IRAK4-deficient humans no longer predisposed to S. aureus skin infections. Thus, clonally expanded γδ T cells represent a mechanism for long-lasting immunity against recurrent S. aureus skin infections.

Selective autonomic stimulation of the AV node fat pad to control rapid post-operative atrial arrhythmias.

Junctional ectopic tachycardia (JET) and atrial fibrillation (AF) occur in patients recovering from open-heart surgery (OHS). Pharmacologic treatment is used for the control of post-operative atrial arrhythmias (POAA), but is associated with side effects. There is a need for a reversible, modulated solution to rate control. We propose a non-pharmacologic technique that can modulate AV nodal conduction in a selective fashion. Ten mongrel dogs underwent OHS. Stimulation of the anterior right (AR) and inferior right (IR) fat pad (FP) was done using a 7-pole electrode. The IR was more effective in slowing the ventricular rate (VR) to AF (52 +/- 20 vs. 15 +/- 10%, p = 0.003) and JET (12 +/- 7 vs. 0 +/- 0%, p = 0.02). Selective site stimulation within a FP region could augment the effect of stimulation during AF (57 +/- 20% (maximum effect) vs. 0 +/- 0% (minimum effect), p<0.001). FP stimulation at increasing stimulation voltage (SV) demonstrated a voltage-dependent effect (8 +/- 14% (low V) vs. 63 +/- 17 (high V) %, p<0.001). In summary, AV node fat pad stimulation had a selective effect on the AV node by decreasing AV nodal conduction, with little effect on atrial activity.

Staphylococcus aureus Epicutaneous Exposure Drives Skin Inflammation via IL-36-Mediated T Cell Responses.

Staphylococcus aureus colonization contributes to skin inflammation in diseases such as atopic dermatitis, but the signaling pathways involved are unclear. Herein, epicutaneous S. aureus exposure to mouse skin promoted MyD88-dependent skin inflammation initiated by IL-36, but not IL-1α/ß, IL-18, or IL-33. By contrast, an intradermal S. aureus challenge promoted MyD88-dependent host defense initiated by IL-1ß rather than IL-36, suggesting that different IL-1 cytokines trigger MyD88 signaling depending on the anatomical depth of S. aureus cutaneous exposure. The bacterial virulence factor PSMα, but not α-toxin or δ-toxin, contributed to the skin inflammation, which was driven by IL-17-producing γδ and CD4+ T cells via direct IL-36R signaling in the T cells. Finally, adoptive transfer of IL-36R-expressing T cells to IL-36R-deficient mice was sufficient for mediating S. aureus-induced skin inflammation. Together, this study defines a previously unknown pathway by which S. aureus epicutaneous exposure promotes skin inflammation involving IL-36R/MyD88-dependent IL-17 T cell responses.