Lysozyme binds to elastin and protects elastin from elastase-mediated degradation

UVA Exposure Combined with Glycation of the Dermis Are Two Catalysts for Skin Aging and Promotes a Favorable Environment to the Appearance of Elastosis

Skin aging is the result of superimposed intrinsic (individual) and extrinsic (e.g., UV exposure or nutrition) aging. Previous works have reported a relationship between UV irradiation and glycation in the aging process, leading, for example, to modified radical species production and the appearance of AGEs (advanced glycosylation end products) in increasing quantities, particularly glycoxidation products like pentosidine. In addition, the colocalization of AGEs and elastosis has also been observed. We first investigated the combination of the glycation reaction and UVA effects on a reconstructed skin model to explain their cumulative biological effect. We found that UVA exposure combined with glycation had the ability to intensify the response for specific markers: for example, MMP1 or MMP3 mRNA, proteases involved in extracellular matrix degradation, or proinflammatory cytokine, IL1α, protein expression. Moreover, the association of glycation and UVA irradiation is believed to promote an environment that favors the onset of an elastotic-like phenomenon: mRNA coding for elastin, elastase, and tropoelastin expression is increased. Secondly, because the damaging effects of UV radiation in vivo might be more detrimental in aged skin than in young skin due to increased accumulation of pentosidine and the exacerbation of alterations related to chronological aging, we studied the biological effect of soluble pentosidine in fibroblasts grown in monolayers. We found that pentosidine induced upregulation of CXCL2, IL8, and MMP12 mRNA expression (inflammatory and elastotic markers, respectively). Tropoelastin protein expression (elastin precursor) was also increased. In conclusion, fibroblasts in monolayers cultured with soluble pentosidine and tridimensional in vitro skin constructs exposed to the combination of AGEs and UVA promote an inflammatory state and an alteration of the dermal compartment in relation to an elastosis-like environment.

The Immune System in Human Milk: A Historic Perspective

BACKGROUND

Human milk contains a remarkable array of immunological agents that evolved over millions of years to protect the recipient human infant. Furthermore, much of the protection persists long after weaning. However, the scientists who first discovered some components of this immune system have rarely been acknowledged.

SUMMARY

The scientists who made many fundamental immunological discoveries concerning the immune system in human milk include Alfred François Donné, Paul Ehrlich, Lars Å. Hanson, and Jules Bordet. Based upon their discoveries, a wealth of antimicrobial, anti-inflammatory, and immunomodulating agents, and living, activated leukocytes in human milk were later revealed during the last half of the 20th and the first part of the 21st century. Moreover, it was found that human milk enhances the colonization of commensal bacteria that aid to protect the human infant. Key Message: Their discoveries helped to revitalize breastfeeding in industrialized countries during the past several decades.

Pseudomonas aeruginosa elastase (LasB) as a therapeutic target

Why is P. aeruginosa LasB elastase an attractive target for antivirulence therapy and what is the state-of-the art in LasB inhibitor design and development?

The Skin Interactome: A Holistic "Genome-Microbiome-Exposome" Approach to Understand and Modulate Skin Health and Aging

Higher demands on skin care cosmetic products for strong performance drive intense research to understand the mechanisms of skin aging and design strategies to improve overall skin health. Today we know that our needs and influencers of skin health and skin aging change throughout our life journey due to both extrinsic factors, such as environmental factors and lifestyle factors, as well as our intrinsic factors. Furthermore, we need to consider our microflora, a collection of micro-organisms such as bacteria, viruses, and fungi, which is a living ecosystem in our gut and on our skin, that can have a major impact on our health. Here, we are viewing a holistic approach to understand the collective effect of the key influencers of skin health and skin aging both reviewing how each of them impact the skin, but more importantly to identify molecular conjunction pathways of these different factors in order to get a better understanding of the integrated “genome-microbiome-exposome” effect. For this purpose and in order to translate molecularly the impact of the key influencers of skin health and skin aging, we built a digital model based on system biology using different bioinformatics tools. This model is considering both the positive and negative impact of our genome (genes, age/gender), exposome: external (sun, pollution, climate) and lifestyle factors (sleep, stress, exercise, nutrition, skin care routine), as well as the role of our skin microbiome, and allowed us in a first application to evaluate the effect of the genome in the synthesis of collagen in the skin and the determination of a suitable target for boosting pro-collagen synthesis. In conclusion, we have, through our digital holistic approach, defined the skin interactome concept, as an advanced tool to better understand the molecular genesis of skin aging and further develop a strategy to balance the influence of the exposome and microbiome to protect, prevent, and delay the appearance of skin aging signs and preserve good skin health condition. In addition, this model will aid in identifying and optimizing skin treatment options based on external triggers, as well as helping to design optimal treatments modulating the intrinsic pathways.

Elastofibroma dorsi: What's new?

Elastofibroma dorsi is a rare slowgrowing soft tissues tumor. The lesion usually grows near the shoulder but could also involve other location. Pathogenesis of elastofibroma dorsi is still unknown and in the literature, there are mostly described case report or case series. The aim of our study is to summarize the recent innovation in the histology and immunoistochemical finding about elastofibroma and update the radiological algorithm of diagnosis.

Does lysozyme play a role in the pathogenesis of COPD?

Elastic fiber injury is an important process in the pathogenesis of chronic obstructive pulmonary disease (COPD), particularly with regard to the development of pulmonary emphysema. Damage to these fibers results in uneven distribution of mechanical forces in the lung, leading to dilatation and rupture of alveolar walls. While the role of various enzymes and oxidants in this process has been well-documented, we propose that a previously unsuspected agent, lysozyme, may contribute significantly to the changes in elastic fibers observed in this disease. Studies from our laboratory have previously shown that lysozyme preferentially binds to elastic fibers in human emphysematous lungs. On the basis of this finding, it is hypothesized that the attachment of lysozyme to these fibers enhances their susceptibility to injury, and further impairs the transfer of mechanical forces in the lung, leading to increased alveolar wall damage and enhanced progression of COPD. The hypothesized effects of lysozyme are predicated on its interaction with hyaluronan (HA), a long-chain polysaccharide that is found in close proximity to elastic fibers. By preventing the binding of HA to elastic fibers in COPD, lysozyme may interfere with the protective effect of this polysaccharide against enzymes and oxidants that degrade these fibers. Furthermore, the loss of the hydrating effect of HA on these fibers may impair their elastic properties, greatly increasing the probability of their fragmentation in response to mechanical forces. The proposed hypothesis may explain why the content of HA is significantly lower in the lungs of COPD patients. It may also contribute to the design of clinical trials involving the use of exogenously administered HA as a potential treatment for COPD.

Immunohistochemical patterns in the interfollicular Caucasian scalps: influences of age, gender, and alopecia

Skin ageing and gender influences on the scalp have been seldom studied. We revisited the changes in the interfollicular scalp. The study was performed on a population of 650 volunteers (300 women and 350 men) for over 7 years. Three age groups were selected in both genders, namely, subjects aged 20–35, 50–60, and 60–70 years. The hair status was further considered according to nonalopecic and alopecic patterns and severity (discrete, moderate, and severe). Biopsies from the parietal area were processed for immunohistochemistry. Stromal cells were distinguished according to the presence of vimentin, Factor XIIIa, CD117, and versican. Blood and lymphatic vessels were highlighted by Ulex europaeus agglutinin-1 and human podoplanin immunoreactivities, respectively. Actinic elastosis was identified by the lysozyme coating of elastic fibres. The epidermis was explored using the CD44 variant 3 and Ki67 immunolabellings. Biplot analyses were performed. Immunohistochemistry revealed a prominent gender effect in young adults. Both Factor XIIIa+ dermal dendrocytes and the microvasculature size decreased with scalp ageing. Alopecia changes mimicked stress-induced premature senescence.

A new role for an old antimicrobial: lysozyme c-1 can function to protect malaria parasites in Anopheles mosquitoes

BACKGROUND

Plasmodium requires an obligatory life stage in its mosquito host. The parasites encounter a number of insults while journeying through this host and have developed mechanisms to avoid host defenses. Lysozymes are a family of important antimicrobial immune effectors produced by mosquitoes in response to microbial challenge.

METHODOLOGY/PRINCIPAL FINDINGS

A mosquito lysozyme was identified as a protective agonist for Plasmodium. Immunohistochemical analyses demonstrated that Anopheles gambiae lysozyme c-1 binds to oocysts of Plasmodium berghei and Plasmodium falciparum at 2 and 5 days after infection. Similar results were observed with Anopheles stephensi and P. falciparum, suggesting wide occurrence of this phenomenon across parasite and vector species. Lysozyme c-1 did not bind to cultured ookinetes nor did recombinant lysozyme c-1 affect ookinete viability. dsRNA-mediated silencing of LYSC-1 in Anopheles gambiae significantly reduced the intensity and the prevalence of Plasmodium berghei infection. We conclude that this host antibacterial protein directly interacts with and facilitates development of Plasmodium oocysts within the mosquito.

CONCLUSIONS/SIGNIFICANCE

This work identifies mosquito lysozyme c-1 as a positive mediator of Plasmodium development as its reduction reduces parasite load in the mosquito host. These findings improve our understanding of parasite development and provide a novel target to interrupt parasite transmission to human hosts.

The riddle of genuine skin microrelief and wrinkles

Wrinkles result from distinct structural changes occurring in specific parts of the dermis and subcutaneous tissue. There is a need for evidenced-based cosmetology identifying and quantifying the different aspects of wrinkling. Histology allows to detect specific changes associated with particular types of wrinkles. Four main types of wrinkles can thus be recognized, including the atrophic crinkling rhytids, the permanent elastotic creases, the dynamic expression lines, and the gravitational folds. Each type usually develops on specific skin regions exhibiting distinct microanatomical characteristics. Whereas skin microrelief, expression lines and skin folds appear clearly marked at the histological level, only little dermal changes are identified under other reducible or permanent wrinkles compared with the skin immediately adjacent to them. Distinguishing different types of wrinkles brings more precision to the clinical practice. This is of importance because the different types of wrinkles respond differently to cosmetic, dermatological and surgical treatments.

The defensive role of lysozyme in human gingiva in inflammatory periodontal disease

BACKGROUND AND OBJECTIVE

The presence of lysozyme in human gingiva has not previously been demonstrated. In this study, we looked for evidence for the potential role of lysozyme as a protector of gingival elastic fibres. The objective of this study was also to determine the ex vivo susceptibility to hydrolysis of gingival elastic fibres from patients with or without periodontal disease by human leukocyte elastase and by human cathepsin G.

MATERIALS AND METHODS

Using gingival tissue sections from eight control, 10 gingivitis and 10 periodontitis patients, we evaluated the area fraction occupied by gingival elastic fibres (after selective staining) by the use of automated image analysis. In the ex vivo experiments, serial tissue sections from four control, four gingivitis, four young periodontitis and four aged periodontitis patients were submitted to the action of human leukocyte elastase and cathepsin G, after which enzymatic activities were determined by image analysis. Indirect immunodetection of lysozyme was also done on tissue sections for all patients included in this study.

RESULTS

Large variations of the area fraction occupied by elastic fibres were observed in human gingiva from young and aged patients with and without periodontal disease. In control and gingivitis patients, leukocyte elastase and cathepsin G had high comparable elastin solubilizing activities. With young and aged periodontitis patients, the two serine proteinases had weak elastin solubilizing activities. Lysozyme appeared to be present at the periphery of gingival elastic fibres in periodontitis patients.

CONCLUSION

Lysozyme can be considered an important natural protector of elastic fibres in pathological gingiva.

The immune system in human milk and the developing infant

The concept of the immune system in human milk emerged in the 1970s from clinical and laboratory observations made between the late 18th through the mid-20th centuries. The discovery of living leukocytes in human milk in 1970 was the final link to the chain of evidence that culminated in the concept. The concept was later expanded to include not only antimicrobial but also anti-inflammatory and immunoregulatory agents. These agents evolved to compensate for developmental delays in the immune system during infancy. Indeed, that explains the defense by human milk against common infectious diseases in infancy, necrotizing enterocolitis in preterm infants, and immune-mediated disorders such as Crohn's disease in later childhood. These diverse evolutionary outcomes underscore the superiority of human milk for the nutrition of human infants. Finally, other components of the immune system in human milk and their fate and functions in the developing infant may well be discovered in the near future.

Elastin changes during chronological and photo-ageing: the important role of lysozyme

Cutaneous ageing, as a result of combined chronological and photo-ageing in sun-exposed areas, is accompanied by major modifications of the elastic fibres. We aimed to investigate qualitative and quantitative changes of dermal elastin fibres during cutaneous chronological and photo-ageing and the involvement of lysozyme in these processes. Morphological, age-related changes and variations in the relative elastin content in sun-protected (buttock) and sun-exposed (forearm and face) skin of healthy volunteers were studied (145 samples). The deposition of lysozyme in elastin fibres was studied using light and immuno-electron microscopy and taking into consideration the relative efficacy of different UV wavebands (UVA or SSR (solar simulated radiation)). Our studies also included the proteolytic degradation of elastin by human leucocyte elastase (HLE) in situ. Our results indicate a reduction of elastin content with age in sun-protected and sun-exposed skin, associated for the latter with high elastin content, resulting in elastosis. Total UVA (320-400 nm), and in particular long wave UVA (UVA-1, 340-400 nm), induces lysozyme deposition in elastin fibres to a higher extent than solar simulated radiation (SSR, 280-400 nm). Immuno-electron microscopy revealed lysozyme association with the electron-dense granular amorphous elastin structures, corresponding to a basophilic degeneration induced by sun exposure. Lysozyme has no elastolytic activity in situ; however, its binding to elastin limits elastin degradation by human leucocyte elastase (HLE). In addition, a direct inhibitory effect of lysozyme on HLE was observed. Our data suggest that lysozyme prevents elastin degradation by HLE after binding to the damaged parts of the elastin network and by direct lysozyme-HLE interaction, which reduces HLE proteolytic activity. These observations contribute to a better understanding of the chronological and photo-induced changes of the dermal elastic network.

Accumulation of elafin in actinic elastosis of sun-damaged skin: elafin binds to elastin and prevents elastolytic degradation

Elafin has a primary structure with two functional domains; a transglutaminase substrate domain at the N-terminus and a protease inhibitor domain at the C-terminus. Elafin expression has so far been reported only for epithelial tissues. Accumulation of elafin was immunohistochemically detected in the actinic elastosis of sun-damaged skin. Exposure of normal skin to UVA induced elafin expression that colocalized with elastic fibers. Incubation of synthetic transglutaminase substrate domain of elafin and elastin molecules in the presence of tissue transglutaminase in vitro resulted in the formation of a higher molecular complex on SDS-PAGE. Elafin expression was not detected in normal cultured skin fibroblasts, but was induced by UVA irradiation at both messenger RNA and protein levels. When radiolabeled insoluble elastin was incubated with recombinant full-length elafin and tissue transglutaminase, insoluble elastin became more resistant to neutrophil elastase digestion. These results indicate that (1) dermal fibroblasts potentially express elafin on UV irradiation, (2) UV-mediated elafin interacts with elastin, and (3) the elafin-elastin complex protects elastic fibers from elastolytic degradation, leading to the accumulation of elastic fibers in the actinic elastosis of sun-damaged skin. The transglutaminase substrate moiety of elafin plays an important role in anchoring elafin at its proper sites of action during UV-induced aging processes.

Changes in Matrix Gene and Protein Expressions After Single or Repeated Exposure to One Minimal Erythemal Dose of Solar-simulated Radiation in Human Skin In Vivo

Damage to the skin extracellular matrix (ECM) is the hallmark of long-term exposure to solar UV radiation. The aim of our study was to investigate the changes induced in unexposed human skin in vivo after single or repeated (five times a week for 6 weeks) exposure to 1 minimal erythemal dose (MED) of UV solar-simulated radiation. Morphological and biochemical analyses were used to evaluate the structural ECM components and the balance between the degrading enzymes and their physiologic inhibitors. A three-fold increase in matrix metalloproteinase 2 messenger RNA (mRNA) (P < 0.02, unexposed versus exposed) was observed after both single and repeated exposures. Fibrillin 1 mRNA level was increased by chronic exposure (P < 0.02) and unaltered by a single MED. On the contrary, a single MED significantly enhanced mRNA levels of interleukin-1alpha (IL-1alpha), IL-1beta (P < 0.02) and plasminogen activator inhibitor-1 (P < 0.05). Immunohistochemistry demonstrated a significant decrease in Type-I procollagen localized just below the dermal-epidermal junction in both types of exposed sites. At the same location, the immunodetected tenascin was significantly enhanced, whereas a slight increase in Type-III procollagen deposits was also observed in chronically exposed areas. Although we were unable to observe any change in elastic fibers in chronically exposed buttock skin, a significant increase in lysozyme and alpha-1 antitrypsin deposits on these fibers was observed. These results demonstrate the existence of a differential regulation, after chronic exposure compared with an acute one, of some ECM components and inflammatory mediators.

From skin microrelief to wrinkles. An area ripe for investigation

Skin microrelief alters progressively with age. Wrinkles do not result from these changes but are superimposed upon them. Wrinkles result from structural changes in the epidermis, dermis and hypodermis. Four types of wrinkles can be recognized. Type 1 wrinkles are atrophic. Type 2 wrinkles are elastotic. Type 3 wrinkles are expressional. Type 4 wrinkles are gravitational. Each type of wrinkle is characterized by distinct microanatomical changes and each type of wrinkle develops in specific skin regions. Each is likely to respond differently to treatment. Skin microrelief and skin folds can be identified on histological examination. By contrast, only minimal dermal changes are found beneath permanent or reducible wrinkles compared with immediately adjacent skin. A series of objective and non-invasive methods is available to quantify the severity of wrinkling.

Evolution of the mammary gland defense system and the ontogeny of the immune system

A decisive event in the evolution of mammals from synapsid reptiles was the modification of ventral thoracic-abdominal epidermal glands to form the mammary gland. The natural selection events that drove the process may have been the provision of certain immunological agents in dermal secretions of those nascent mammals. This is mirrored by similar innate immune factors in mammalian sebum and in protherian and eutherian milks. On the basis of studies of existing mammalian orders, it is evident that immune agents in milk such as immunoglobulins, iron-binding proteins, lysozyme, oligosaccharides, and leukocytes compensate for developmental delays in early postnatal production of antimicrobial factors. At least in human milk, anti-inflammatory and immunomodulating agents also evolved to provide different types of protection for the offspring. In addition, investigations reveal that the types or concentrations of immunological agents in milk vary depending upon the type of placenta, lactation pattern, and environment of the species.

Growth hormone and prolactin--molecular and functional evolution

Growth hormone, prolactin, the fish hormone, somatolactin, and related mammalian placental hormones, including placental lactogen, form a family of polypeptide hormones that share a common tertiary structure. They produce their biological effects by interacting with and dimerizing specific single transmembrane-domain receptors. The receptors belong to a superfamily of cytokine receptors with no intrinsic tyrosine kinase, which use the Jak-Stat cascade as a major signalling pathway. Hormones and receptors are thought to have arisen as a result of gene duplication and subsequent divergence early in vertebrate evolution. Mammalian growth hormone and prolactin show a slow basal evolutionary rate of change, but with episodes of accelerated evolution. These occurred for growth hormone during the evolution of the primates and artiodactyls and for prolactin in lineages leading to rodents, elephants, ruminants, and man. Placental lactogen has probably evolved independently on three occasions, from prolactin in rodents and ruminants and from growth hormone in man. Receptor sequences also show variable rates of evolution, corresponding partly, but not completely, with changes in the ligand. A principal biological role of growth hormone, the control of postnatal growth, has remained quite consistent throughout vertebrate evolution and is largely mediated by insulin-like growth factors. Prolactin has many and diverse roles. In relation to lactation, the relative roles of growth hormone and prolactin vary between species. Correlation between the molecular and functional evolution of these hormones is very incomplete, and it is likely that many important functional adaptations involved changes in regulatory elements, for example, altering tissue of origin or posttranscriptional processing, rather than change of the structures of the proteins themselves.

Aspiration cytology of elastofibroma dorsi: case report with ultrastructural and immunohistochemical findings

Elastofibroma is a well-recognized tumor-like process which typically occurs in the soft tissue of the shoulder. Although fine-needle aspiration (FNA) represents a quick and simple method for definitive diagnosis, the possibility of a false-negative diagnosis is high due to the hypocellularity of the smears. However, a high index of suspicion based on the clinical presentation of a firm mass in a typical location in an elderly person, usually female, aids in the diagnosis. We describe the FNA findings of elastofibroma dorsi in an 89-yr-old woman which, although hypocellular, contained diagnostic aggregates of petaloid globules within a collagenous matrix. The cytologic material showed a green-yellow autofluorescence of the altered elastic fibers with ultraviolet light. Transmission electron microscopy revealed an elongated beaded appearance with small electron densities and obliteration of the central elastin core. The presence of a hypocellular aspirate with autofluorescent elastic fibers should suggest the possibility of elastofibroma dorsi.

The effect of lysozyme on elastase-mediated injury

Previous studies by this laboratory demonstrated that lysozyme is increased in human pulmonary emphysema, and that it preferentially binds to elastic fibers, which undergo degradation in this disease. In the current investigation, the relationship between lysozyme and elastic fiber injury was further examined, both in vitro and in vivo. The effect of exogenously administered egg-white lysozyme on pancreatic elastase-induced injury was determined using a biosynthetically radiolabeled extracellular matrix preparation mainly composed of elastic fibers. Although matrix treated with lysozyme showed attachment of the protein to elastic fibers, there was no significant increase in elastolysis compared with untreated controls following exposure to either 1 microg/ml or 100 ng/ml of pancreatic elastase. However, lysozyme did impair the ability of hyaluronan (HA) to prevent elastase injury to elastic fibers. Matrix samples sequentially treated with lysozyme and HA, then incubated with 1 microg/ml or 100 ng/ml of pancreatic elastase, showed significantly increased elastolysis compared with those treated with HA alone. Since HA is closely associated with elastic fibers in vivo, the ability of lysozyme to enhance elastolysis was further tested in an animal model of emphysema induced by intratracheal administration of porcine pancreatic elastase. Animals exposed to aerosolized lysozyme prior to elastase administration showed significantly increased airspace enlargement. The mean linear intercept of the lysozyme-treated animals was 123 microm compared with 75 microm for controls receiving aerosolized water (P < 0.0001). These findings suggest that lysozyme may not be an innocuous component of the inflammatory response associated with pulmonary emphysema, but may actually play a role in the pathogenesis of the disease.

Pseudomonas aeruginosa protease IV enzyme assays and comparison to other Pseudomonas proteases

Pseudomonas aeruginosa secretes multiple proteases that have been implicated as virulence factors and the detection of each specific enzyme can be difficult to determine. Unlike the three Pseudomonas enzymes that have been well characterized (elastase A, elastase B, and alkaline protease), the activity of protease IV in multiple assays has yet to be described. This study defines new assays for Pseudomonas proteases and compares protease IV activity to the activities of elastase A, elastase B, and alkaline protease. Six in vitro assays were studied: zymography, elastin congo red assay, staphylolytic assay, colorimetric peptide assay, solid-phase colorimetric peptide assay, and poly-l-lysine degradation. Casein zymography distinguished protease IV from elastase B and alkaline protease, and gelatin zymography differentiated all four proteases. The elastin congo red assay detected mainly elastase B while the staphylolytic assay was specific for elastase A. Protease IV activity was assayed specifically by the colorimetric assay and two new assays, the solid-phase colorimetric assay and degradation of poly-L-lysine in the presence of EDTA. Alkaline protease could be specifically assayed by poly-L-lysine degradation in the presence of N-alpha-p-tosyl-L-lysine chloromethyl ketone. The results identified three specific assays for protease IV, a new assay specific for alkaline protease, and showed that protease IV has a distinct enzymatic specificity relative to the three other Pseudomonas proteases.

Elastofibroma dorsi: elaboration of cytologic features and review of its pathogenesis

Elastofibroma is a slow-growing soft tissue lesion characteristically found between the inferior scapula and chest wall. Because it behaves clinically in a benign manner, fine-needle aspiration (FNA) represents the simplest and quickest method of obtaining a definitive diagnosis, thus obviating more invasive means of obtaining a tissue diagnosis. However, due to the nature of this lesion a correct diagnosis can inadvertently be missed. Herein we describe the findings of a recent FNA that obtained abundant diagnostic material and elaborate upon the spectrum of cytologic features of the elastic fibers that can be identified. These features should be recognized, since aspiration biopsy in elastofibromas can lead to hypocellular smears. In addition, we discuss recent developments in the pathophysiology of elastic fibers and their application toward understanding the generation of an elastofibroma.

Characterization of the elastin binding domain in the cell-surface 25-kDa elastin-binding protein of staphylococcus aureus (EbpS)

Our previous studies have established that a cell-surface 25-kDa elastin-binding protein of Staphylococcus aureus (EbpS) mediates binding of this pathogen to the extracellular matrix protein elastin. Results from binding assays examining the activity of various EbpS fragments suggested that the elastin recognition domain is contained within the first 59 amino acids. In this report, we have used functional analyses with synthetic peptides and recombinant truncated forms of EbpS to localize the elastin binding domain to a 21-amino acid region contained within residues 14-34 of EbpS. Further evidence for the importance of this domain was obtained by demonstrating that the inhibitory activity of anti-EbpS antibodies on staphylococcal elastin binding was neutralized when these antibodies were pre-absorbed with a truncated recombinant EbpS construct containing residues 1-34. Overlapping synthetic peptides corresponding to EbpS residues 14-36 were then generated and tested for elastin binding activity to define further the elastin binding domain, and results from these studies showed that sequences spanning amino acids Gln14-Asp23, Asp17-Asp23, and Thr18-Glu34 inhibit binding of Staphylococcus aureus to elastin. Our analyses indicate that the hexameric sequence Thr18-Asn-Ser-His-Gln-Asp23 is the minimal sequence common to all active synthetic peptides, proteolytic fragments, and recombinant constructs of EbpS. Furthermore, substitution of Asp23 with Asn abrogated the blocking activity of the synthetic peptides, demonstrating the requirement for a charged amino acid at this location. The composite data indicate that staphylococcal elastin binding is mediated by a discrete domain defined by short peptide sequences in the amino-terminal extracellular region of EbpS.

Mexoryl SX: a broad absorption UVA filter protects human skin from the effects of repeated suberythemal doses of UVA

There is now considerable evidence that chronic UVA exposure induces damage in animal and human skin; however, little is known about UVA protection of human skin. The aim of this study is to evaluate the efficacy of Mexoryl SX, a broad UVA absorber (lamada max = 345 nm) against UVA-induced changes in human skin. The regimen of UVA exposure (13 weeks with increasing suberythemal doses) induces intense pigmentation with no erythema. Skin hydration and elasticity decrease, whereas total skin thickness, assessed by echography, remains unchanged. Irradiated epidermis reveals a significant thickening of the stratum corneum, an absence of hyperplasia and an increase in the expression of the protective iron-storage protein ferritin. No significant alterations are seen using antisera against type IV collagen or laminin, suggesting that the dermal-epidermal junction (DEJ) is mainly preserved. In dermis, enhanced expression of tenascin is seen just below the DEJ but type I procollagen, which is localized at the same site, is unaltered. Although we are unable to visualize any changes in elastic network organization using Luna staining or specific antiserum directed against human elastin, we notice an increased deposition of lysozyme or alpha-1 antitrypsin on elastin fibres. Mexoryl SX (5%) efficiently prevents these alterations. Thus, these results suggest that UVA photoprotection can prevent early putative alterations leading to photoageing.

Evolution of immunologic functions of the mammary gland and the postnatal development of immunity

Physiologic delays in production of immune factors occur in mammals including Homo sapiens. This finding is counter to a basic tenet of biologic evolution, because such delays increase the risk of infections. The disadvantage is, however, offset by defense factors in milk of the species in whom the developmental delay occurs. Reciprocal relationships between the production of immune factors by the lactating mammary gland and the production of those defense agents during early infancy are found in all investigated mammalian species. Thus, the evolution of these processes is closely related. Certain immunologic components of milk are highly conserved, whereas others vary according to the species. The variations most likely evolved by genetic mutations and natural selection. In addition, the immune composition of mammalian milks is associated with developmental delays in the same immunologic agents. Furthermore, most closely related mammals, such as humans and chimpanzees, are most similar in the defense agents in their milks and the corresponding developmental delays in their immune systems. Defense factors in human milk include antimicrobial agents (secretory IgA, lactoferrin, lysozyme, glycoconjugates, oligosaccharides, and digestive products of milk lipids), antiinflammatory factors (antioxidants, epithelial growth factors, cellular protective agents, and enzymes that degrade mediators of inflammation), immunomodulators (nucleotides, cytokines, and antiidiotypic antibodies), and leukocytes (neutrophils, macrophages, and lymphocytes). Because of a lack of geographic/ethnic variation in the immunologic composition of human milk and corresponding immunologic delays in infants, these evolutionary processes seem stable. This is supported by investigations of diverse populations that indicate that this evolutionary outcome is highly beneficial to human infants.

The spectral dependence for UVA-induced cumulative damage in human skin

The wavelength dependence for UVA-induced cumulative damage was investigated in human skin. Epidermal changes (stratum corneum thickening, viable epidermal thickening sunburn cell production), as well as dermal alterations (lysozyme deposition, inflammation), were used as indices of cumulative photoperturbation. UVA wavelengths between 320 nm and 345 nm were more effective than longer wavelengths (360-400 nm) in inducing viable epidermal thickening. Similarly, the shorter wavelengths (320-345 nm) elicited more sunburn cells, although these differences did not reach statistical significance. All UVA bands were equally effective in inducing the dermal markers. At equal fluences, wavelengths > 400 nm produced no measurable cutaneous alterations. These findings suggest that (i) chronic epidermal and dermal damages have different spectral dependence and (ii) the action spectrum for dermal damage in the UVA is broad, extending up to 400 nm, and is different from the acute erythema spectrum in humans.