Response to Comment on "A commensal strain of Staphylococcus epidermidis protects against skin neoplasia" by Nakatsuji et al.

Kozmin et al. contend that observations previously reported regarding the antimicrobial and antitumor activities of 6-N-hydroxy aminopurine (6-HAP) were incorrect. Their conclusions rely on poorly characterized reagents and focus strictly on in vitro techniques without validation in relevant mammalian model systems. We are pleased to be able to illuminate the weaknesses in their technical comment. The totality of current results continues to support our original conclusion that a strain of the common human commensal skin bacterium, Staphylococcus epidermidis, produces 6-HAP that can inhibit tumor growth

Vaccinia virus binds to the scavenger receptor MARCO on the surface of keratinocytes.

Patients with altered skin immunity, such as individuals with atopic dermatitis (AD), can have a life-threatening disruption of the epidermis known as eczema vaccinatum after vaccinia virus (VV) infection of the skin. Here, we sought to better understand the mechanism(s) by which VV associates with keratinocytes. The class A scavenger receptor known as MARCO (macrophage receptor with collagenous structure) is expressed on human and mouse keratinocytes and found to be abundantly expressed in the skin of patients with AD. VV bound directly to MARCO, and overexpression of MARCO increased susceptibility to VV infection. Furthermore, ligands with affinity for MARCO, or excess soluble MARCO, competitively inhibited VV infection. These findings indicate that MARCO promotes VV infection and highlights potential new therapeutic strategies for prevention of VV infection in the skin

HSV-1 exploits the innate immune scavenger receptor MARCO to enhance epithelial adsorption and infection

HSV-1 is an important epithelial pathogen and has the potential for significant morbidity in humans. Here we demonstrate that a cell surface scavenger receptor, macrophage receptor with collagenous structure (MARCO), previously thought to enhance antiviral defense by enabling nucleic acid recognition, is usurped by HSV-1 and functions together with heparan sulfate proteoglycans to mediate adsorption to epithelial cells. Ligands of MARCO dramatically inhibit HSV-1 adsorption and infection of human keratinocytes and protect mice against infection. HSV-1 glycoprotein C (gC) closely co-localizes with MARCO at the cell surface, and gC binds directly to purified MARCO with high affinity. Increasing MARCO expression enhances HSV-1 infection while MARCO-/- mice have reduced susceptibility to infection by HSV-1. These findings demonstrate that HSV-1 binds to MARCO to enhance its capacity for disease, and suggests a new therapeutic target to alter pathogenicity of HSV-1 in skin infection

Antibodies Elicited by Inactivated Propionibacterium acnes-Based Vaccines Exert Protective Immunity and Attenuate the IL-8 Production in Human Sebocytes: Relevance to Therapy for Acne Vulgaris

Propionibacterium acnes is a key pathogen involved in the progression of inflammation in acne vulgaris. We examined whether vaccination against P. acnes suppressed P. acnes-induced skin inflammation. Inactivation of P. acnes with heat was employed to create a P. acnes-based vaccine. Intranasal immunization in mice with this inactivated vaccine provoked specific antibodies against P. acnes. Most notably, immunization with inactivated vaccines generated in vivo protective immunity against P. acnes challenge and facilitated the resolution of ear inflammation in mice. In addition, antibodies elicited by inactivated vaccines effectively neutralized the cytotoxicity of P. acnes and attenuated the production of proinflammatory cytokine IL-8 in human sebocyte SZ95 cells. Intranasal immunization using heat-inactivated P. acnes-based vaccines provided a simple modality to develop acne vaccines. These observations highlight the concept that development of vaccines targeting microbial products may represent an alternative strategy to conventional antibiotic therapy

TLR2 expression is increased in rosacea and stimulates enhanced serine protease production by keratinocytes.

A diverse environment challenges skin to maintain temperature, hydration, and electrolyte balance while also maintaining normal immunological function. Rosacea is a common skin disease that manifests unique inflammatory responses to normal environmental stimuli. We hypothesized that abnormal function of innate immune pattern recognition could explain the enhanced sensitivity of patients with rosacea, and observed that the epidermis of patients with rosacea expressed higher amounts of Toll-like receptor 2 (TLR2) than normal patients. Increased expression of TLR2 was not seen in other inflammatory skin disorders such as atopic dermatitis or psoriasis. Overexpression of TLR2 on keratinocytes, treatment with TLR2 ligands, and analysis of TLR2-deficient mice resulted in a calcium-dependent release of kallikrein 5 from keratinocytes, a critical protease involved in the pathogenesis of rosacea. These observations show that abnormal TLR2 function may explain enhanced inflammatory responses to environmental stimuli and can act as a critical element in the pathogenesis of rosacea

IL-4Rα Blockade by Dupilumab Decreases Staphylococcus aureus Colonization and Increases Microbial Diversity in Atopic Dermatitis.

Dupilumab is a fully human antibody to interleukin-4 receptor α that improves the signs and symptoms of moderate to severe atopic dermatitis (AD). To determine the effects of dupilumab on Staphylococcus aureus colonization and microbial diversity on the skin, bacterial DNA was analyzed from swabs collected from lesional and nonlesional skin in a double-blind, placebo-controlled study of 54 patients with moderate to severe AD randomized (1:1) and treated with either dupilumab (200 mg weekly) or placebo for 16 weeks. Microbial diversity and relative abundance of Staphylococcus were assessed by DNA sequencing of 16S ribosomal RNA, and absolute S. aureus abundance was measured by quantitative PCR. Before treatment, lesional skin had lower microbial diversity and higher overall abundance of S. aureus than nonlesional skin. During dupilumab treatment, microbial diversity increased and the abundance of S. aureus decreased. Pronounced changes were seen in nonlesional and lesional skin. Decreased S. aureus abundance during dupilumab treatment correlated with clinical improvement of AD and biomarkers of type 2 immunity. We conclude that clinical improvement of AD that is mediated by interleukin-4 receptor α inhibition and the subsequent suppression of type 2 inflammation is correlated with increased microbial diversity and reduced abundance of S. aureus

A commensal strain of Staphylococcus epidermidis protects against skin neoplasia.

We report the discovery that strains of Staphylococcus epidermidis produce 6-N-hydroxyaminopurine (6-HAP), a molecule that inhibits DNA polymerase activity. In culture, 6-HAP selectively inhibited proliferation of tumor lines but did not inhibit primary keratinocytes. Resistance to 6-HAP was associated with the expression of mitochondrial amidoxime reducing components, enzymes that were not observed in cells sensitive to this compound. Intravenous injection of 6-HAP in mice suppressed the growth of B16F10 melanoma without evidence of systemic toxicity. Colonization of mice with an S. epidermidis strain producing 6-HAP reduced the incidence of ultraviolet-induced tumors compared to mice colonized by a control strain that did not produce 6-HAP. S. epidermidis strains producing 6-HAP were found in the metagenome from multiple healthy human subjects, suggesting that the microbiome of some individuals may confer protection against skin cancer. These findings show a new role for skin commensal bacteria in host defense. Sci Adv 2018 Feb 28; 4(2):eaao450

IL-4R alpha blockade by dupilumab decreases Staphylococcus aureus colonization and increases microbial diversity in atopic dermatitis

Dupilumab is a fully human antibody to interleukin-4 receptor alpha that improves the signs and symptoms of moderate to severe atopic dermatitis (AD). To determine the effects of dupilumab on Staphylococcus aureus colonization and microbial diversity on the skin, bacterial DNA was analyzed from swabs collected from lesional and nonlesional skin in a double-blind, placebo-controlled study of 54 patients with moderate to severe AD randomized (1:1) and treated with either dupilumab (200 mg weekly) or placebo for 16 weeks. Microbial diversity and relative abundance of Staphylococcus were assessed by DNA sequencing of 16S ribosomal RNA, and absolute S. aureus abundance was measured by quantitative PCR. Before treatment, lesional skin had lower microbial diversity and higher overall abundance of S. aureus than nonlesional skin. During dupilumab treatment, microbial diversity increased and the abundance of S. aureus decreased. Pronounced changes were seen in nonlesional and lesional skin. Decreased S. aureus abundance during dupilumab treatment correlated with clinical improvement of AD and biomarkers of type 2 immunity. We conclude that clinical improvement of AD that is mediated by interleukin-4 receptor alpha inhibition and the subsequent suppression of type 2 inflammation is correlated with increased microbial diversity and reduced abundance of S. aureus