Psoriasin (S100A7) is a principal antimicrobial peptide of the human tongue

Antifungal recombinant psoriasin of human origin effectively inhibits fungal growth on denture base

OBJECTIVE

To evaluate the efficacy of recombinant psoriasin as a novel treatment for oral candidiasis by eliminating Candida albicans growth on polymethyl methacrylate denture base.

MATERIALS AND METHODS

Recombinant psoriasin protein was expressed and purified from E. coli, and Candida growth was monitored in vitro with varying concentrations of psoriasin. Subsequently, denture-base polymethyl methacrylate was immersed in psoriasin's solution or voriconazole, and fungal growth on the acrylic base and in the medium was examined by scanning electron microscopy and optical density, respectively. Cellular viability of HeLa and human gingival fibroblast cells treated with psoriasin was measured by methylene blue assay.

RESULTS

The findings reveal an effective antifungal activity of psoriasin, completely inhibiting Candida albicans growth in RPMI at a protein concentration above 400 nM. Immersing the polymethyl methacrylate with 50 μM psoriasin completely eradicates fungal growth. Psoriasin has low cytotoxicity in HeLa cells at a concentration higher than 12 μM and no toxic effect on human gingival fibroblasts.

CONCLUSIONS

This study marks psoriasin as an effective alternative to conventional antifungal treatments for denture stomatitis and a safe alternative to chemical antifungals in dental medicine and beyond.

Acute physiological effects following Bacillus subtilis DE111 oral ingestion - a randomised, double blinded, placebo-controlled study

Previous studies using ileostomy samples from study participants demonstrated that the spore-forming probiotic Bacillus subtilis DE111® can germinate in the small intestine as early as 4 hours after ingestion. Metabolomics, proteomics and sequencing technologies, enabled further analysis of these samples for the presence of hypoglycaemic, hypolipidemic, antioxidant, anti-inflammatory and antihypertensive molecules. In the DE111 treatment group, the polyphenols trigonelline and 2,5-dihydroxybenzoic acid, orotic acid, the non-essential amino acid cystine and the lipokine 12,13-diHome were increased. DE111 also reduced acetylcholine levels in the ileostomy samples, and increased the expression of leucocyte recruiting proteins, antimicrobial peptides and intestinal alkaline phosphatases of the brush border in the small intestine. The combination of B. subtilis DE111 and the diet administered during the study increased the expression of the proteins phosphodiesterase ENPP7, ceramidase ASAH2 and the adipokine Zn-alpha-2-glycoprotein that are involved in fatty acid and lipid metabolism. Acute B. subtilis DE111 ingestion had limited detectable effect on the microbiome, with the main change being its increased presence. These findings support previous data suggesting a beneficial role of DE111 in digestion, metabolism, and immune health that appears to begin within hours of consumption.

Potential biomarker proteins for aspiration pneumonia detected by shotgun proteomics using buccal mucosa samples: a cross-sectional case-control study

BACKGROUND

Aspiration pneumonia (AP), which is a major cause of death in the elderly, does present with typical symptoms in the early stages of onset, thus it is difficult to detect and treat at an early stage. In this study, we identified biomarkers that are useful for the detection of AP and focused on salivary proteins, which may be collected non-invasively. Because expectorating saliva is often difficult for elderly people, we collected salivary proteins from the buccal mucosa.

METHODS

We collected samples from the buccal mucosa of six patients with AP and six control patients (no AP) in an acute-care hospital. Following protein precipitation using trichloroacetic acid and washing with acetone, the samples were analyzed by liquid chromatography and tandem mass spectrometry (LC-MS/MS). We also determined the levels of cytokines and chemokines in non-precipitated samples from buccal mucosa.

RESULTS

Comparative quantitative analysis of LC-MS/MS spectra revealed 55 highly (P values < 0.10) abundant proteins with high FDR confidence (q values < 0.01) and high coverage (> 50%) in the AP group compared with the control group. Among the 55 proteins, the protein abundances of four proteins (protein S100-A7A, eukaryotic translation initiation factor 1, Serpin B4, and peptidoglycan recognition protein 1) in the AP group showed a negative correlation with the time post-onset; these proteins are promising AP biomarker candidates. In addition, the abundance of C-reactive protein (CRP) in oral samples was highly correlated with serum CRP levels, suggesting that oral CRP levels may be used as a surrogate to predict serum CRP in AP patients. A multiplex cytokine/chemokine assay revealed that MCP-1 tended to be low, indicating unresponsiveness of MCP-1 and its downstream immune pathways in AP.

CONCLUSION

Our findings suggest that oral salivary proteins, which are obtained non-invasively, can be utilized for the detection of AP.

Induction of Endogenous Antimicrobial Peptides to Prevent or Treat Oral Infection and Inflammation

Antibiotics are often used to treat oral infections. Unfortunately, excessive antibiotic use can adversely alter oral microbiomes and promote the development of antibiotic-resistant microorganisms, which can be difficult to treat. An alternate approach could be to induce the local transcription and expression of endogenous oral antimicrobial peptides (AMPs). To assess the feasibility and benefits of this approach, we conducted literature searches to identify (i) the AMPs expressed in the oral cavity; (ii) the methods used to induce endogenous AMP expression; and (iii) the roles that expressed AMPs may have in regulating oral inflammation, immunity, healing, and pain. Search results identified human neutrophil peptides (HNP), human beta defensins (HBD), and cathelicidin AMP (CAMP) gene product LL-37 as prominent AMPs expressed by oral cells and tissues. HNP, HBD, and LL-37 expression can be induced by micronutrients (trace elements, elements, and vitamins), nutrients, macronutrients (mono-, di-, and polysaccharides, amino acids, pyropeptides, proteins, and fatty acids), proinflammatory agonists, thyroid hormones, and exposure to ultraviolet (UV) irradiation, red light, or near infrared radiation (NIR). Localized AMP expression can help reduce infection, inflammation, and pain and help oral tissues heal. The use of a specific inducer depends upon the overall objective. Inducing the expression of AMPs through beneficial foods would be suitable for long-term health protection. Additionally, the specialized metabolites or concentrated extracts that are utilized as dosage forms would maintain the oral and intestinal microbiome composition and control oral and intestinal infections. Inducing AMP expression using irradiation methodologies would be applicable to a specific oral treatment area in addition to controlling local infections while regulating inflammatory and healing processes.

Mutagenesis of the Loop 3 α-Helix of Neisseria gonorrhoeae TdfJ Inhibits S100A7 Binding and Utilization

Neisseria gonorrhoeae causes the sexually transmitted infection (STI) gonorrhea, which afflicts over 80 million people each year. No vaccine is available to prevent gonorrhea. The pathogen alters the expression and antigenic presentation of key surface molecules, making the identification of suitable vaccine targets difficult. The human host utilizes metal-binding proteins to limit free essential transition metal ions available to invading pathogens, limiting their infective potential, a process called nutritional immunity. To overcome this, N. gonorrhoeae employs outer membrane TonB-dependent transporters (TdTs) that bind host nutritional immunity proteins and strip them of their metal cargo. The TdTs are well conserved, and some play key roles in establishing infections, making them promising vaccine targets. One TdT, TdfJ, recognizes human S100A7, a zinc-binding protein that inhibits the proliferation of other pathogens via zinc sequestration. N. gonorrhoeae uses TdfJ to strip and internalize zinc from S100A7. TdfJ contains a conserved α-helix finger in extracellular loop 3; a similar α-helix in loop 3 of another gonococcal TdT, TbpA, plays a critical role in the interaction between TbpA and human transferrin. Therefore, we hypothesized that the TdfJ loop 3 helix (L3H) participates in interactions with S100A7. We determined the affinity between wild-type TdfJ and S100A7 and then generated a series of mutations in the TdfJ L3H. Our study revealed that mutagenesis of key residues within the L3H reduced S100A7 binding and zinc piracy by the gonococcus, with profound effects seen with substitutions at residues K261 and R262. Taken together, these data suggest a key role for the TdfJ L3H in subverting host metal restriction.

Transitory Shifts in Skin Microbiota Composition and Reductions in Bacterial Load and Psoriasin following Ethanol Perturbation

Personal care and hygiene regimens may substantially alter the composition of the skin microbiota through direct and indirect mechanisms. An understanding of the timescales of commensal skin microbiota reestablishment following perturbation is required to inform consumer safety risk assessment, and support product development. In the current investigation, the microbiota of the volar and dorsal forearm of 10 volunteers was sampled immediately before and after wiping with 70% ethanol and at up to 24 h afterwards. Quantitative PCR and amplicon sequencing were used to measure microbial load and composition, and concentrations of the antimicrobial peptide psoriasin were measured using an enzyme-linked immunosorbent assay (ELISA). Ethanol wiping significantly reduced the total bacterial abundance at 2 h post-wipe. Recovery was observed after 6 h for total bacterial populations and for Staphylococcus epidermidis depending on the site tested. Microbiome diversity recovered by 6 h after wiping. Psoriasin concentrations were highly variable between volunteers, ranging from 42 to 1,569 ng/mL, and dorsal concentrations were significantly higher than volar concentrations (P < 0.05). For most of the volunteers, the application of ethanol decreased psoriasin concentrations, particularly for the dorsal samples, but the overall effect was not significant. This work extends observations of skin microbiome stability and demonstrates resilience in a key antimicrobial peptide.

IMPORTANCE An understanding of the timescales of commensal skin microbiota reestablishment following perturbation is required to inform consumer safety risk assessment and support product development. Following ethanol exposure, total bacterial populations and microbiome diversity recovered after 6 h. For most of the volunteers, the application of ethanol decreased psoriasin concentrations, but the overall effect was not significant. This work extends observations of skin microbiome stability and demonstrates resilience in a key antimicrobial peptide.

Evolution of innate defense in human skin

More often as compared to other barrier systems (gastrointestinal, urogenital, and respiratory linings) human skin over millions of years has been subject to fundamental changes in structure and function. When life on land started, the first changes consisted in the formation of a coherent impermeable stratum corneum. Two-legged locomotion was followed by loss of body hair and formation of sweat glands. Major changes took place after the agricultural revolution, investigating settlements with domestication of animals and plants. Living together after giving up nomadic life, hairless skin became a battlefield for pathogens, members of the skin microbiome, and arthropod visits. Human skin became exceptional in showing a boosted, highly developed immune system which is much more complex as compared to the "skins" of other species. A recently found skin disinfection system ("Cationic Intrinsically Disordered Antimicrobial Peptides, CIDAMPs") dates back to the origins of life and still is active in present-day integuments. As a skin-restricted and effective principle, keratinocyte- myeloid synergy (KMS) is recognized. As a consequence of such highly developed immune defense, the basic contributions of KMS - cells (keratinocytes, neutrophils, macrophages) in regulating innate immunity is emphasized. Antimicrobial peptides and chemokines became major keratinocyte products. The formation of impermeable str. corneum membrane has enabled KMS - cells to accumulate within upper skin levels and cause a special group of human skin diseases, pustular dermatoses.

Protein S100-A7 Derived from Digested Dentin Is a Critical Molecule for Dentin Pulp Regeneration

Dentin consists of inorganic hard tissue and organic dentin matrix components (DMCs). Various kinds of bioactive molecules are included in DMCs and some of them can be released after digestion by endogenous matrix metalloproteinases (MMPs) in the caries region. Digested DMCs induced by MMP20 have been reported to promote pulpal wound healing processes, but the released critical molecules responsible for this phenomenon are unclear. Here, we identified protein S100-A7 as a critical molecule for pulpal healing in digested DMCs by comprehensive proteomic approaches and following pulp capping experiments in rat molars. In addition, immunohistochemical results indicated the specific distribution of S100-A7 and receptor for advanced glycation end-products (RAGE) as receptor for S100-A7 in the early stage of the pulpal healing process, and following accumulation of CD146-positive stem cells in wounded pulp. Our findings indicate that protein S100-A7 released from dentin by MMP20 might play a key role in dentin pulp regeneration.

The novel interaction between Neisseria gonorrhoeae TdfJ and human S100A7 allows gonococci to subvert host zinc restriction

Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea, a global disease that is difficult to treat and for which there is no vaccine. This pathogen employs an arsenal of conserved outer membrane proteins called TonB-dependent transporters (TdTs) that allow the gonococcus to overcome nutritional immunity, the host strategy of sequestering essential nutrients away from invading bacteria to handicap infectious ability. N. gonorrhoeae produces eight known TdTs, of which four are utilized for acquisition of iron or iron chelates from host-derived proteins or xenosiderophores produced by other bacteria. Of the remaining TdTs, two of them, TdfH and TdfJ, facilitate zinc uptake. TdfH was recently shown to bind Calprotectin, a member of the S100 protein family, and subsequently extract its zinc, which is then internalized by N. gonorrhoeae. Like Calprotectin, other S100s are also capable of binding transition metals such as zinc and copper, and thus have demonstrated growth suppression of numerous other pathogens via metal sequestration. Considering the functional and structural similarities of the TdTs and of the S100s, as well as the upregulation in response to Zn limitation shown by TdfH and TdfJ, we sought to evaluate whether other S100s have the ability to support gonococcal growth by means of zinc acquisition and to frame this growth in the context of the TdTs. We found that both S100A7 and S10012 are utilized by N. gonorrhoeae as a zinc source in a mechanism that depends on the zinc transport system ZnuABC. Moreover, TdfJ binds directly to S100A7, from which it internalizes zinc. This interaction is restricted to the human version of S100A7, and zinc presence in S100A7 is required to fully support gonococcal growth. These studies highlight how gonococci co-opt human nutritional immunity, by presenting a novel interaction between TdfJ and human S100A7 for overcoming host zinc restriction.

Neisseria gonorrhoeae causes the common sexually-transmitted infection gonorrhea. This bacteria’s ability to rapidly acquire antibiotic resistance factors, coupled with the lack of any effective vaccine to prevent infection, has resulted in a disease that poses a global threat and may become untreatable. A group of gonococcal outer membrane proteins called TonB-dependent transporters (TdTs) have been implicated as promising vaccine targets, as they are well-conserved and expressed across gonococcal isolates and play a vital role in allowing the pathogen to acquire essential nutrients during infection of the human host. Here, we describe the conservation and regulation of TdfJ, a gonococcal TdT whose homologues are ubiquitous in the genus Neisseria. We show that TdfJ binds directly to S100A7, a host protein that normally sequesters zinc away from invading pathogens. This novel interaction enables N. gonorrhoeae to strip S100A7 of chelated zinc for its own use. Furthermore, we show that another zinc-binding human protein, S100A12, is also utilized by N. gonorrhoeae as a zinc source by an as-yet-unidentified mechanism. This study provides insight into the functional role of the TdTs during infection and highlights these proteins as promising targets for both vaccine and antimicrobial therapy development.

Preparation of the Oxidized and Reduced Forms of Psoriasin (S100A7)

Human S100A7 (psoriasin) is a metal-chelating host-defense protein expressed by epithelial cells. S100A7 possesses two Cys residues that generate two redox isoforms of the protein. In the oxidized form (S100A7_ox), Cys47 and Cys96 form an intramolecular disulfide bond, whereas these residues exist as free thiols in the reduced form (S100A7_red). In this chapter, we provide a step-by-step protocol for the purification of S100A7_ox and S100A7_red that affords each protein in high yield and purity. In this procedure, S100A7 is expressed in Escherichia coli BL21(DE3), and the homodimer is obtained following ammonium sulfate precipitation, folding, and column chromatography. Treatment of S100A7 with 1,4-dithiothreitol (DTT) affords S100A7_red. A Cu(II)-catalyzed oxidation reaction is employed to obtain S100A7_ox. A RP-HPLC method that allows for baseline separation of S100A7_ox and S100A7_red is provided, as well as a biochemical Zn(II)-binding assay that can be employed to evaluate the functional integrity of S100A7.

Bioinorganic Explorations of Zn(II) Sequestration by Human S100 Host-Defense Proteins

The human innate immune system launches a metal-withholding response to starve invading microbial pathogens of essential metal nutrients. Zn(II)-sequestering proteins of the human S100 family contribute to this process and include calprotectin (CP, S100A8/S100A9 oligomer, calgranulin A/B oligomer), S100A12 (calgranulin C), and S100A7 (psoriasin). This Perspective highlights recent advances in the Zn(II) coordination chemistry of these three proteins, as well as select studies that evaluate Zn(II) sequestration as an antimicrobial mechanism.

Biochemical and Functional Evaluation of the Intramolecular Disulfide Bonds in the Zinc-Chelating Antimicrobial Protein Human S100A7 (Psoriasin)

Human S100A7 (psoriasin) is a metal-chelating protein expressed by epithelial cells. It is a 22-kDa homodimer with two EF-hand domains per subunit and two transition-metal-binding His3Asp sites at the dimer interface. Each subunit contains two cysteine residues that can exist as free thiols (S100A7red) or as an intramolecular disulfide bond (S100A7ox). Herein, we examine the disulfide bond redox behavior, the Zn(II) binding properties, and the antibacterial activity of S100A7, as well as the effect of Ca(II) ions on these properties. In agreement with prior work [Hein, K. Z., et al. (2013) Proc. Natl. Acad. Sci. U. S. A. 112, 13039-13044], we show that apo S100A7ox is a substrate for the mammalian thioredoxin system; however, negligible reduction of the disulfide bond is observed for Ca(II)- and Zn(II)-bound S100A7ox. Furthermore, metal binding depresses the midpoint potential of the disulfide bond. S100A7ox and S100A7red each coordinate 2 equiv of Zn(II) with subnanomolar affinity in the absence and presence of Ca(II) ions, and the cysteine thiolates in S100A7red do not form a third high-affinity Zn(II) site. These results refute a prior model implicating the Cys thiolates of S100A7red in high-affinity Zn(II) binding [Hein, K. Z., et al. (2013) Proc. Natl. Acad. Sci. U. S. A. 112, 13039-13044]. S100A7ox and the disulfide-null variants show comparable Zn(II)-depletion profiles; however, only S100A7ox exhibits antibacterial activity against select bacterial species. Metal substitution experiments suggest that the disulfide bonds in S100A7 may enhance metal sequestration by the His3Asp sites and thereby confer growth inhibitory properties to S100A7ox.

RETRACTED: Straticyte demonstrates prognostic value over oral epithelial dysplasia grade for oral potentially malignant lesion assessment

OBJECTIVES

Straticyte™ was previously shown to be a more effective prognostic assessment than the current standard of care, histopathological dysplasia grading, to assess progression risk of oral epithelial dysplasia to invasive cancer [Hwang JT, Gu YR, Shen M, Ralhan R, Walfish PG, Pritzker KP, et al. Individualized five-year risk assessment for oral premalignant lesion progression to cancer. Oral Surg Oral Med Oral Pathol Oral Radiol. 2017;123:374-81]. In this follow-up study, our aim is to confirm the prognostic value of Straticyte using an independent cohort of oral biopsy cases previously assessed as epithelial dysplasia of various grades.

MATERIALS AND METHODS

Using Visiopharm image analysis system, we analyzed an independent retrospective cohort of 51 oral biopsy samples with known outcomes and a follow-up history of up to 12years, to verify Straticyte, an individualized 5-year risk assessment for progression of oral potentially malignant lesions to invasive squamous cell carcinoma.

RESULTS

Straticyte classified the lesions more accurately than histopathological oral epithelial dysplasia grading for risk for progression to cancer over five years. The sensitivity of low-risk vs. non-low-risk Straticyte groups was 100% compared to 68% for mild vs. non-mild dysplasia. The sensitivity of high-risk vs. non-high-risk Straticyte was 71% compared to 3% for severe vs. non-severe dysplasia. Furthermore, the Negative Predictive Value (NPV) for Straticyte was 100% for low-risk vs. non-low-risk, whereas the NPV for mild vs. non-mild dysplasia was 38%.

CONCLUSION

In this cohort, Straticyte ascertains as a more useful assessment for risk of cancer progression in oral potentially malignant lesions than oral epithelial dysplasia grade.

Platelet-released growth factors induce psoriasin in keratinocytes: Implications for the cutaneous barrier

Millions of patients around the world suffer minor or major extremity amputation due to progressive wound healing complications of chronic or infected wounds, the therapy of which remains a challenge. One emerging therapeutic option for the treatment of these complicated wounds is the local application of an autologous thrombocytes concentrate lysate (e.g. platelet-released growth factors ((PRGF)) or Vivostat PRF^®) that contains a multitude of chemokines, cytokines and growth factors and is therefore supposed to stimulate the complex wound healing process. Although PRGF and Vivostat PRF^® are already used successfully to support healing of chronic, hard-to-heal and infected wounds the underlying molecular mechanisms are not well understood. Psoriasin, also termed S100A7, is a multifunctional antimicrobial protein expressed in keratinocytes and is involved in various processes such as wound-healing, angiogenesis, innate immunity and immune-modulation. In this study, we investigated the influence of PRGF on psoriasin expression in human primary keratinocytes in vitro and the influence of Vivostat PRF^® on psoriasin expression in experimentally generated skin wounds in vivo. PRGF treatment of primary keratinocytes caused a significant concentration- and time-dependent increase of psoriasin gene and protein expression in vitro that were partially mediated by the epidermal growth factor receptor (EGFR) and the interleukin-6 receptor (IL-6R). In accordance with these cell culture data, Vivostat PRF^® induced a significant psoriasin gene and protein expression when applied to artificially generated skin wounds in vivo. The observed psoriasin induction in keratinocytes may contribute to the wound healing-promoting effects of therapeutically used thrombocyte concentrate lysates.

Derivation of marker gene signatures from human skin and their use in the interpretation of the transcriptional changes associated with dermatological disorders

Numerous studies have explored the altered transcriptional landscape associated with skin diseases to understand the nature of these disorders. However, data interpretation represents a significant challenge due to a lack of good maker sets for many of the specialized cell types that make up this tissue, whose composition may fundamentally alter during disease. Here we have sought to derive expression signatures that define the various cell types and structures that make up human skin, and demonstrate how they can be used to aid the interpretation of transcriptomic data derived from this organ. Two large normal skin transcriptomic datasets were identified, one RNA-seq (n = 578), the other microarray (n = 165), quality controlled and subjected separately to network-based analyses to identify clusters of robustly co-expressed genes. The biological significance of these clusters was then assigned using a combination of bioinformatics analyses, literature, and expert review. After cross comparison between analyses, 20 gene signatures were defined. These included expression signatures for hair follicles, glands (sebaceous, sweat, apocrine), keratinocytes, melanocytes, endothelia, muscle, adipocytes, immune cells, and a number of pathway systems. Collectively, we have named this resource SkinSig. SkinSig was then used in the analysis of transcriptomic datasets for 18 skin conditions, providing in-context interpretation of these data. For instance, conventional analysis has shown there to be a decrease in keratinization and fatty metabolism with age; we more accurately define these changes to be due to loss of hair follicles and sebaceous glands. SkinSig also highlighted the over-/under-representation of various cell types in skin diseases, reflecting an influx in immune cells in inflammatory disorders and a relative reduction in other cell types. Overall, our analyses demonstrate the value of this new resource in defining the functional profile of skin cell types and appendages, and in improving the interpretation of disease data. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

An orthologue of the host-defense protein psoriasin (S100A7) is expressed in frog skin

Host-defense peptides and proteins are vital for first line protection against bacteria. Most host-defense peptides and proteins common in vertebrates have been studied primarily in mammals, while their orthologues in non-mammalian vertebrates received less attention. We found that the European Common Frog Rana temporaria expresses a protein in its skin that is evolutionarily related to the host-defense protein S100A7. This prompted us to test if the encoded protein, which is an important microbicidal protein in human skin, shows similar activity in frogs. The R. temporaria protein lacks the zinc-binding sites that are key to the antimicrobial activity of human S100A7 at neutral pH. However, despite being less potent, the R. temporaria protein does compromise bacterial membranes at low pH, similar to its human counterpart. We postulate that, while amphibian S100A7 likely serves other functions, the capacity to compromise bacterial cell membranes evolved early in tetrapod evolution.

Transition Metals and Virulence in Bacteria

Transition metals are required trace elements for all forms of life. Due to their unique inorganic and redox properties, transition metals serve as cofactors for enzymes and other proteins. In bacterial pathogenesis, the vertebrate host represents a rich source of nutrient metals, and bacteria have evolved diverse metal acquisition strategies. Host metal homeostasis changes dramatically in response to bacterial infections, including production of metal sequestering proteins and the bombardment of bacteria with toxic levels of metals. In response, bacteria have evolved systems to subvert metal sequestration and toxicity. The coevolution of hosts and their bacterial pathogens in the battle for metals has uncovered emerging paradigms in social microbiology, rapid evolution, host specificity, and metal homeostasis across domains. This review focuses on recent advances and open questions in our understanding of the complex role of transition metals at the host-pathogen interface.

Pathophysiology of chronic rhinosinusitis, pharmaceutical therapy options

Research in immunology has brought great progress in knowledge of inflammatory processes in the last 2 decades, which also has an impact on the upper airways. Our understanding of the pathophysiology of chronic rhinosinusitis developed from a rather mechanistic point of view with a focus on narrow clefts and mucociliary clearance to the appreciation of a complex network of immunological pathways forming the basis of disease. We today differentiate various forms of inflammation, we start to understand complex immune-regulatory networks and the reasons for their failure, and have already developed innovative approaches for therapy for the most severely ill subjects. Due to this new knowledge in inflammation and remodeling processes within mucosal tissue, specifically on the key driving factors, new diagnostic tools and therapeutic approaches for chronic rhinosinusitis have developed; the differentiation of endotypes based on pathophysiological principles will be crucial for the use of innovative therapies, mostly humanized monoclonal antibodies. Several hundred of those antibodies are currently developed for various indications and will impact our specialty as well as pneumology to a great extent.

Disulphide-reduced psoriasin is a human apoptosis-inducing broad-spectrum fungicide

The unexpected resistance of psoriasis lesions to fungal infections suggests local production of an antifungal factor. We purified Trichophyton rubrum-inhibiting activity from lesional psoriasis scale extracts and identified the Cys-reduced form of S100A7/psoriasin (redS100A7) as a principal antifungal factor. redS100A7 inhibits various filamentous fungi, including the mold Aspergillus fumigatus, but not Candida albicans. Antifungal activity was inhibited by Zn(2+), suggesting that redS100A7 interferes with fungal zinc homeostasis. Because S100A7-mutants lacking a single cysteine are no longer antifungals, we hypothesized that redS100A7 is acting as a Zn(2+)-chelator. Immunogold electron microscopy studies revealed that it penetrates fungal cells, implicating possible intracellular actions. In support with our hypothesis, the cell-penetrating Zn(2+)-chelator TPEN was found to function as a broad-spectrum antifungal. Ultrastructural analyses of redS100A7-treated T. rubrum revealed marked signs of apoptosis, suggesting that its mode of action is induction of programmed cell death. TUNEL, SYTOX-green analyses, and caspase-inhibition studies supported this for both T. rubrum and A. fumigatus. Whereas redS100A7 can be generated from oxidized S100A7 by action of thioredoxin or glutathione, elevated redS100A7 levels in fungal skin infection indicate induction of both S100A7 and its reducing agent in vivo. To investigate whether redS100A7 and TPEN are antifungals in vivo, we used a guinea pig tinea pedes model for fungal skin infections and a lethal mouse Aspergillus infection model for lung infection and found antifungal activity in both in vivo animal systems. Thus, selective fungal cell-penetrating Zn(2+)-chelators could be useful as an urgently needed novel antifungal therapeutic, which induces programmed cell death in numerous fungi.

The Etiology and Pathogenesis of Chronic Rhinosinusitis: a Review of Current Hypotheses

Chronic rhinosinusitis (CRS) is a broad clinical syndrome that is characterized by prolonged mucosal inflammation of the nose and paranasal sinuses, and is typically divided into two subtypes based on the presence or absence of nasal polyps. The etiology and pathogenesis of both forms remain areas of active research. Over the last 15 years, a number of hypotheses have been proposed to explain all or part of the clinical CRS spectrum. These hypotheses reflect the concept that CRS results from a dysfunctional interplay between individual host characteristics and factors exogenous to the host. Six broad theories on CRS etiology and pathogenesis are discussed as follows: (1) the "fungal hypothesis," (2) the "superantigen hypothesis," (3) the "biofilm hypothesis," and (4) the "microbiome hypothesis," all of which emphasize key environmental factors, and (5) the "eicosanoid hypothesis" and (6) the "immune barrier hypothesis," which describe specific host factors. These theories are reviewed, and the evidence supporting them is critically appraised.

Manganese and microbial pathogenesis: sequestration by the Mammalian immune system and utilization by microorganisms

Bacterial and fungal pathogens cause a variety of infectious diseases and constitute a significant threat to public health. The human innate immune system represents the first line of defense against pathogenic microbes and employs a range of chemical artillery to combat these invaders. One important mechanism of innate immunity is the sequestration of metal ions that are essential nutrients. Manganese is one nutrient that is required for many pathogens to establish an infective lifestyle. This review summarizes recent advances in the role of manganese in the host-pathogen interaction and highlights Mn(II) sequestration by neutrophil calprotectin as well as how bacterial acquisition and utilization of manganese enables pathogenesis.

ICON: chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a public health problem that has a significant socio-economic impact. Moreover, the complexity of this disease due to its heterogeneous nature based on the underlying pathophysiology - leading to different disease variants - further complicates our understanding and directions for the most appropriate targeted treatment strategies. Several International/national guidelines/position papers and/or consensus documents are available that present the current knowledge and treatment strategies for CRS. Yet there are many challenges to the management of CRS especially in the case of the more severe and refractory forms of disease. Therefore, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), a collaboration between EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus (ICON) on Chronic Rhinosinusitis. The purpose of this ICON on CRS is to highlight the key common messages from the existing guidelines, the differences in recommendations as well as the gaps in our current knowledge of CRS, thus providing a concise reference. In this document we discuss the definition of the disease, its relevance, pharmacoeconomics, pathophysiology, phenotypes and endotypes, genetics and risk factors, natural history and co-morbidities as well as clinical manifestations and treatment options in both adults and children comprising pharmacotherapy, surgical interventions and more recent biological approaches. Finally, we have also highlighted the unmet needs that wait to be addressed through future research.

Transcription profiling reveals potential mechanisms of dysbiosis in the oral microbiome of rhesus macaques with chronic untreated SIV infection

A majority of individuals infected with human immunodeficiency virus (HIV) have inadequate access to antiretroviral therapy and ultimately develop debilitating oral infections that often correlate with disease progression. Due to the impracticalities of conducting host-microbe systems-based studies in HIV infected patients, we have evaluated the potential of simian immunodeficiency virus (SIV) infected rhesus macaques to serve as a non-human primate model for oral manifestations of HIV disease. We present the first description of the rhesus macaque oral microbiota and show that a mixture of human commensal bacteria and “macaque versions” of human commensals colonize the tongue dorsum and dental plaque. Our findings indicate that SIV infection results in chronic activation of antiviral and inflammatory responses in the tongue mucosa that may collectively lead to repression of epithelial development and impact the microbiome. In addition, we show that dysbiosis of the lingual microbiome in SIV infection is characterized by outgrowth of Gemella morbillorum that may result from impaired macrophage function. Finally, we provide evidence that the increased capacity of opportunistic pathogens (e.g. E. coli) to colonize the microbiome is associated with reduced production of antimicrobial peptides.

Damage-associated molecular patterns and their receptors in upper airway pathologies

Inflammation of the nasal (rhinitis) and sinus mucosa (sinusitis) are prevalent medical conditions of the upper airways that are concurrent in many patients; hence the terminology "rhinosinusitis". The disease status is further defined to be "chronic" in case symptoms persist for more than 12 weeks without resolution. A diverse spectrum of external factors including viral and bacterial insults together with epithelial barrier malfunctions could be implicated in the chronicity of the inflammatory responses in chronic rhinosinusitis (CRS). However, despite massive research efforts in an attempt to unveil the pathophysiology, the exact reason for a lack of resolution still remains poorly understood. A novel set of molecules that could be implicated in sustaining the inflammatory reaction may be found within the host itself. Indeed, besides mediators of inflammation originating from outside, some endogenous intracellular and/or extracellular matrix (ECM) components from the host can be released into the extracellular space upon damage induced during the initial inflammatory reaction where they gain functions distinct from those during normal physiology. These "host-self" molecules are known to modulate inflammatory responses under pathological conditions, potentially preventing resolution and contributing to the development of chronic inflammation. These molecules are collectively classified as damage-associated molecular patterns (DAMPs). This review summarizes the current knowledge regarding DAMPs in upper airway pathologies, also covering those that were previously investigated for their intracellular and/or ECM functions often acting as an antimicrobial agent or implicated in tissue/cell homeostasis, and for which their function as a danger signaling molecule was not assessed. It is, however, of importance to assess these molecules again from a point of view as a DAMP in order to further unravel the pathogenesis of CRS.

Cnidarian-microbe interactions and the origin of innate immunity in metazoans

Most epithelia in animals are colonized by microbial communities. These resident microbes influence fitness and thus ecologically important traits of their hosts, ultimately forming a metaorganism consisting of a multicellular host and a community of associated microorganisms. Recent discoveries in the cnidarian Hydra show that components of the innate immune system as well as transcriptional regulators of stem cells are involved in maintaining homeostasis between animals and their resident microbiota. Here I argue that components of the innate immune system with its host-specific antimicrobial peptides and a rich repertoire of pattern recognition receptors evolved in early-branching metazoans because of the need to control the resident beneficial microbes, not because of invasive pathogens. I also propose a mutual intertwinement between the stem cell regulatory machinery of the host and the resident microbiota composition, such that disturbances in one trigger a restructuring and resetting of the other.

Antimicrobial peptides and proteins of the horse--insights into a well-armed organism

Antimicrobial peptides play a pivotal role as key effectors of the innate immune system in plants and animals and act as endogenous antibiotics. The molecules exhibit an antimicrobial activity against bacteria, viruses, and eukaryotic pathogens with different specificities and potencies depending on the structure and amino-acid composition of the peptides. Several antimicrobial peptides were comprehensively investigated in the last three decades and some molecules with remarkable antimicrobial properties have reached the third phase of clinical studies. Next to the peptides themselves, numerous organisms were examined and analyzed regarding their repertoire of antimicrobial peptides revealing a huge number of candidates with potencies and properties for future medical applications. One of these organisms is the horse, which possesses numerous peptides that are interesting candidates for therapeutical applications in veterinary medicine. Here we summarize investigations and knowledge on equine antimicrobial peptides, point to interesting candidates, and discuss prospects for therapeutical applications.

Pathophysiology of Chronic Rhinosinusitis with Nasal Polyp

Background

Chronic rhinosinusitis (CRS) is a common inflammatory condition of the paranasal sinuses and nasal passages. CRS with nasal polyp (CRSwNP) is a subtype of CRS, and the pathogenesis of CRSwNP remains largely unclear.

Methods

This article reviews the literature regarding the pathophysiology of CRSwNP.

Results

Evidence suggests that altered innate immunity, adaptive immunity, tissue remodeling, and/or effects of microorganisms may play a role in the development of CRSwNP. Aberrant arachidonic acid metabolism may also contribute to the pathogenesis of CRSwNP in patients with aspirin-exacerbated respiratory disease.

Conclusion

There have been significant advances in the understanding pathophysiology of CRSwNP. Additional research is needed to elucidate these mechanisms and to determine their relative importance in the pathogenesis of CRSwNP.

Psoriasin: key molecule of the cutaneous barrier?

Psoriasin (S100 A7) was discovered two decades ago as a protein abundantly expressed in psoriatic keratinocytes. Even though much scientific research has been carried out on the characterization of psoriasin, only recent studies point to an important role of psoriasin as an antimicrobial and immunomodulatory protein in skin and other epithelia. In this review, we provide an overview of the major findings in psoriasin research and discuss novel studies highlighting the role of psoriasin as an important effector molecule of the cutaneous barrier.

S100A7/psoriasin expression in the human lung: unchanged in patients with COPD, but upregulated upon positive S. aureus detection

BACKGROUND

Progressive airway inflammation and susceptibility to the airway colonisation and infection are characteristic for the pathophysiology of chronic obstructive pulmonary disease (COPD). Antimicrobial peptides (AMPs) are central to the function of the innate host immune response against microbial pathogens and are regulators of inflammation and immunity. S100A7/psoriasin, a recently described AMP, is an essential component of the human epithelia against invading pathogens and acts as an effector molecule of the host innate defence in the skin. We hypothesized that S100A7/psoriasin is involved in the airway mucosal immunity and differently regulated and expressed in the lung during progression of COPD.

METHODS

S100A7/psoriasin gene expression was assessed in bronchial biopsies and bronchoalveolar lavage (BAL) fluid cells of healthy controls and COPD patients. Using confocal microscopy and immunohistochemistry, the protein expression of S100A7/psoriasin was investigated.

RESULTS

Here, we report that S100A7/psoriasin, the major antimicrobial peptide of the human skin, is constitutively expressed in perinuclear granules of human bronchial epithelial cells and alveolar macrophages. Whereas typical activators of the innate immune response like TLR ligands and cytokines induced the upregulation of CXCL-8 mRNA and release of CXCL-8 by epithelial cells, S100A7/psoriasin mRNA expression was not modulated. To investigate a potential association of S100A7/psoriasin with COPD, S100A7/psoriasin mRNA expression was assessed in bronchial biopsies and BAL fluid cells of patients at different stages of COPD and controls. Overall, 10 healthy individuals and 34 COPD patients were enrolled in this study. We found an association of S100A7/psoriasin mRNA expression with bacterial detection in the tracheobronchial system (p = 0.0304), which was the strongest in individuals positive for with S. aureus (p = 0.0005). However, S100A7/psoriasin mRNA expression was not altered during the progression of COPD.

CONCLUSIONS

S100A7/psoriasin gene expression is unchanged in the airways during COPD. The newly identified association of S100A7/psoriasin with S. aureus may provide new insights into the antimicrobial defence response of the human airways, leading to the induction of S100A7/psoriasin upon microbial challenge.

Psoriasin (S100A7) is a major Escherichia coli-cidal factor of the female genital tract

The female urogenital tract requires an efficient defense against bacteria, potentially derived from the adjacent intestinal tract. We have thus sought to identify the factors that protect against Escherichia coli (E. coli) in the female genital tract. Vaginal fluid from healthy human donors consistently killed E. coli in vitro and vaginal epithelium strongly expressed and secreted psoriasin. Psoriasin was constitutively produced in an organotypic vaginal epithelium model, and exposure of these cells to supernatants of E. coli cultures led to an enhanced psoriasin expression. Secreted psoriasin in vaginal fluids accounted for approximately 2.5-3% of total protein. Fractionation of vaginal fluids by high performance liquid chromatography (HPLC) showed that psoriasin co-eluted with a peak of E. coli killing activity. Our data show that normal vaginal fluid contains a powerful intrinsic antimicrobial defense against E. coli and that psoriasin contributes to the innate immune response of the female genital tract.

Structural and functional characterization of a triple mutant form of S100A7 defective for Jab1 binding

S100A7 (psoriasin) is a calcium- and zinc-binding protein implicated in breast cancer. We have shown previously that S100A7 enhances survival mechanisms in breast cells through an interaction with c-jun activation domain binding protein 1 (Jab1), and an engineered S100A7 triple mutant (Asp(56)Gly, Leu(78)Met, and Gln(88)Lys-S100A7(3)) ablates Jab1 binding. We extend these results to include defined breast cancer cell lines and demonstrate a disrupted S100A7(3)/Jab1 phenotype is maintained. To establish the basis for the abrogated Jab1 binding, we have recombinantly produced S100A7(3), demonstrated that it retains the ability to form an exceptionally thermostable dimer, and solved the three dimensional crystal structure to 1.6 A. Despite being positioned at the dimer interface, the Leu(78)Met mutation is easily accommodated and contributes to a methionine-rich pocket formed by Met(12), Met(15), and Met(34). In addition to altering the surface charge, the Gln(88)Lys mutation results in a nearby rotameric shift in Tyr(85), leading to a substantially reorganized surface cavity and may influence zinc binding. The final mutation of Asp(56) to Gly results in the largest structural perturbation shortening helix IV by one full turn. It is noteworthy that position 56 lies in one of two divergent clusters between S100A7 and the functionally distinct yet highly homologous S100A15. The structure of S100A7(3) provides a unique perspective from which to characterize the S100A7-Jab1 interaction and better understand the distinct functions between S100A7, and it is closely related paralog S100A15.

Evidence for diminished levels of epithelial psoriasin and calprotectin in chronic rhinosinusitis

BACKGROUND

Decreased epithelial expression of mRNA for S100A7 (psoriasin) and S100A8/A9 (calprotectin) has been reported in patients with chronic rhinosinusitis (CRS).

OBJECTIVES

We sought to assess whether the expression of S100 proteins is also altered in the sinonasal cavity of patients with CRS.

METHODS

We determined levels of S100 proteins in nasal lavage fluid and sinonasal tissue extracts from patients with CRS using ELISA and immunohistochemical analysis of nasal polyp tissue from patients with CRS with nasal polyps and uncinate tissue from healthy control subjects, patients with CRSsNP, and patients with CRSwNP.

RESULTS

Expression levels of S100 proteins were decreased compared with those seen in control subjects in nasal lavage fluid from both CRS groups (P < .05). Similarly, tissue expression of these proteins assessed by means of immunohistochemistry demonstrated clear reductions, primarily in the epithelial lining. Interestingly, levels of calprotectin were increased in nasal polyp tissue despite lower levels in lavage fluid. Levels of calprotectin in nasal tissues were correlated with levels of neutrophils, as assessed by means of quantification of neutrophil elastase.

CONCLUSIONS

Several S100 proteins are in the epidermal differentiation complex of genes and have been demonstrated to play a role in maintenance of barrier function and formation of an antimicrobial shield. We demonstrate significantly decreased levels of expression of S100 proteins in the epithelium of patients with CRS, which might lead to diminished innate immune responses and barrier function. Increased levels of calprotectin in nasal polyp tissue might reflect neutrophil recruitment and a compensatory mechanism. Future studies will be important to determine whether reduced levels of S100 proteins lead to decreased antimicrobial responses in the upper airways and sinuses and whether this reduction plays a causative role in CRS pathogenesis and susceptibility to infectious disease.

Perspectives on the etiology of chronic rhinosinusitis

PURPOSE OF REVIEW

This article reviews recent insights surrounding the etiology and pathogenesis of chronic rhinosinusitis. In particular, we highlight the increasing recognition of host-mediated mechanisms in driving mucosal inflammation.

RECENT FINDINGS

Published differences between epithelium from patients with chronic rhinosinusitis and normal controls can be classified into several broad categories. Alterations are reported in the various components of the epithelial innate immune system including epithelial-expressed pattern-recognition receptors (PRRs) and the levels of antimicrobial innate immune effector molecules. Other studies demonstrate differences in the proteins involved in maintaining epithelial barrier integrity. Finally, recent studies show in chronic rhinosinusitis that epithelial-derived cytokines, chemokines and inducible surface proteins are involved in recruiting and activating cells of the adaptive immune system.

CONCLUSION

The sinonasal epithelium provides a mechanical and innate immune barrier to a diverse array of environmental agents. This barrier also plays a key role in regulating the acquired mucosal immune response in the nose. Recent studies suggest that defects in this barrier may foster development of chronic sinonasal inflammation in response to environmental agents, and pathogenic or commensal organisms. The ability to dissect and analyze defects in the inflammatory response in rhinosinusitis may help identify novel targets for drug development.

Alterations in epithelial barrier function and host defense responses in chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is characterized by a chronic symptomatic inflammation of the nasal and paranasal sinus mucosae and is one of the most frequently reported chronic diseases in the United States, with an estimated prevalence of greater than 10% of the general population. Although the pathogenesis of CRS remains poorly understood, there is evidence for a role of bacteria and fungi, as well as the presence of a robust adaptive immune response in the upper airways and sinuses. Recent studies of CRS, as well as several other diseases in the skin and respiratory epithelium, have uncovered evidence that deficiencies in epithelial immune barrier function might compromise the interaction between the host and external immune stimuli. Recent studies suggest the hypothesis that reduced expression of antimicrobial S100 proteins, particularly psoriasin and calprotectin, might lead to increased susceptibility to bacterial and fungal colonization in patients with CRS. The main emphasis of this review will be to highlight the current literature that suggests that a defect in the expression of a broad set of epithelially derived genes might lead to barrier compromise and subsequently a dysfunctional host immune response to environmental agents in patients with CRS.