A Predictive Self-Organizing Multicellular Computational Model of Infant Skin Permeability to Topically Applied Substances

Computational models of skin permeability are typically based on assumptions of fixed geometry and homogeneity of the whole epidermis or of epidermal strata and are often limited to adult skin. Infant skin differs quantitatively from that of the adult in its structure and its functional properties, including its barrier function to permeation. To address this problem, we developed a self-organizing multicellular epidermis model of barrier formation with realistic cell morphology. By modulating the parameters relating to cell turnover reflecting those in adult or infant epidermis, we were able to generate accordingly two distinct models. Emerging properties of these models reflect the corresponding experimentally measured values of epidermal and stratum corneum thickness. Diffusion of an externally applied substance (e.g., caffeine) was simulated by a molecular exchange between the model agents, defined by the individual cells and their surrounding extracellular space. By adjusting the surface concentration and the intercellular exchange rate, the model can recapitulate experimental permeability data after topical exposure. By applying these parameters to an infant model, we were able to predict the caffeine concentration profile in infant skin, closely matching experimental results. This work paves the way for a better understanding of skin physiology and function during the first years of life.

Does the presence of bacterial urinary infection contribute to the development of incontinence-associated dermatitis? A scoping review

OBJECTIVE

Incontinence-associated dermatitis (IAD) is an inflammatory skin condition caused by the repeated exposure to urine and faeces. It is not common for urinary incontinence only to cause IAD, however patients with urinary tract infections (UTIs) are also at increased risk for IAD. This scoping review aimed to provide a summary of the relationship between bacterial urinary infections and IAD.

METHODS

We conducted a scoping review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. PubMed, CINAHL, Medline, and Web of Science were searched for relevant articles from January 2007 through February 2020.

RESULTS

Based on eligibility criteria, 13 research studies and review articles were included. Despite the acknowledged role of bacterial infections can play in IAD and the importance of eradicating infections for the prevention of skin breakdown, there have been limited studies that have investigated how uropathogenic bacteria, in combination with urine, lead to skin damage and IAD. The use of urinary catheters also predisposes to UTIs; however, prevalence/incidence rates of IAD in these patients are not clear, as they were considered as continent of urine in the included studies.

CONCLUSION

Further research is needed to elucidate the mechanisms of how bacteria, in combination with urine, lead to IAD.

The Pathophysiology of Skin Failure vs. Pressure Injury: Conditions That Cause Integument Destruction and Their Associated Implications

INTRODUCTION

Although integument failure commonly is attributed to pressure alone, especially when a wound develops over a bony prominence (pressure injury), all skin failure should not be attributed to pressure injuries.

OBJECTIVE

A systematic review of the literature was conducted to: (1) differentiate the types of integument injury and etiology; (2) describe the anatomic and pathophysiologic factors affecting integument failure; (3) differentiate avoidable vs. unavoidable integumentary injury of nonpressure-related sources; (4) describe factors leading to integument injury, including comorbid and risk factors; and (5) briefly discuss clinical and economic importance of delineating pressure injuries from integument failure and associated risk factors in order to determine the pathophysiology underlying wound development and multiple factors capable of interacting with pressure to synergistically influence integumentary failure.

METHODS

The PubMed database was searched for English-language studies during March 2020 using the key words pathophysiology, etiology, pressure ulcers, pressure injury, pressure wounds, and risk factors.

RESULTS

The PubMed search yielded 1561 publications in total; of these, 59 were selected for review based on their relevance, timeliness, and subject matter, including 50 original studies of any study design, 5 review articles, and 4 public agency reports that addressed the 5 study purpose components.

CONCLUSIONS

Clinicians need to better understand the pathophysiology and classification of integument injuries by underlying etiologies both avoidable and unavoidable. A more accurate diagnosis would lead to more appropriate treatment strategies, an improved quality of care for affected patients, less wasted resources and reduced financial penalties for healthcare providers, and decreased medicolegal claims.

Os Styloideum Resection Complicated by Severe Contact Dermatitis to 2-Octyl Cyanoacrylate: A Case Study

Os styloideum is an accessory wrist bone at the base of the second and third metacarpals. Similar to metacarpal bossing, chronic pain secondary to the development of osteoarthritis and tendon irritation is common. Conservative management consists of splinting and steroid injections, with surgical resection being the definitive treatment. 2-Octyl cyanoacrylate adhesive glue is commonly used to close these and other types of wounds.

PURPOSE

We report the case of a 29-year-old man who developed severe dermatitis following surgical removal of a right dorsal hand mass at the base of the third metacarpal, which had been slowly enlarging and causing pain for 18 months.

METHODS

After unsuccessful conservative management, the mass was resected and the incision was closed with buried monofilament suture and 2-octyl cyanoacrylate skin glue. Upon splint removal due to pain, 6 days postoperatively, severe contact dermatitis resulting in scattered partial- and full-thickness skin necrosis was observed. Local wound care, systemic corticosteroids, and a secondary surgical closure were required for resolution of the skin breakdown.

CONCLUSION

This case demonstrates 2 uncommon occurrences: a rare hand mass and severe contact dermatitis to 2-octyl cyanoacrylate with resultant tissue necrosis. Mass resection is commonly reserved for symptomatic os styloideum. Caution should be used when applying 2-octyl cyanoacrylate under a splint. Removal of glue and steroids provides effective treatment for severe contact dermatitis, but full-thickness injuries may require debridement and secondary closure.

Pathomechanisms of Contact Sensitization

Contact sensitization is the initial process involved in the development of an allergic reaction to xenobiotic environmental substances. Here, we briefly describe the differences between irritant and allergic contact dermatitis. Then, we highlight the essential steps involved in the development of an ACD reaction, i.e., the protein binding of haptens, genetic factors influencing the penetration of sensitizers into the skin, the different mechanisms driving the initial development of an inflammatory cytokine micromilieu enabling the full maturation of dendritic cells, the role of pre- and pro-haptens, antigen presentation and T cell activation via MHC and CD1 molecules, dendritic cell (DC) migration, and potential LC contribution as well as the different T cell subsets involved in ACD. In addition, we discuss the latest publications regarding factors that might influence the sensitizing potential such as repeated sensitizer application, penetration enhancers, humidity of the skin, microbiota, Tregs, and phthalates. Last but not least, we briefly touch upon novel targets for drug development that might serve as treatment options for ACD.

Functional Food und Bioverfügbarkeit im Zielorgan Haut

Reactive free radicals can be produced in the skin by the action of environmental factors, such as sun radiation and toxins. These radicals can damage the DNA, proteins and lipids of the living cells. The consequences can be skin aging, immune suppression and even skin cancer. Humans have developed a protective mechanism against the action of free radicals in the form of antioxidant substances. Several of these antioxidants cannot be produced by humans and have to be acquired via food, such as carotenoids. Optical, non-invasive methods, like resonance Raman spectroscopy, allow a qualitative and quantitative online detection of the kinetics of antioxidants such as carotenoids in the skin. By employing this method it has been shown that the uptake of carotenoids in food can lead to an accumulation in the skin. On the other hand, stress, illness and UV-radiation can reduce the concentration of antioxidant substances in the skin. A high concentration of antioxidant substances is protective and associated with a reduction in skin wrinkling.

Toxalbumin exposures: 12 years' experience of U.S. poison centers

BACKGROUND

Toxalbumins are natural plant toxins purported to be highly toxic. The purpose was to evaluate toxalbumin exposures reported to U.S. poison centers to determine plants involved and their toxicities.

METHODS

A retrospective review of National Poison Data System data on acute toxalbumin exposures with known outcomes from 2000 through 2011 was performed.

RESULTS

There were 1164 exposures. The majority involved one route (1135; 97.5%), mostly ingestions (904; 79.7%) or dermal (166; 14.3%). Most patients developed no effects (694; 59.6%) or minor effects (374; 32.1%). Moderate or major effects occurred in 8.3% with 66.6% ingestions and 23.9% dermal. There were no deaths. Exposures to the plants Ricinus communis and Robinia pseudoacacia were most common (33.8% and 32.9%, respectively), with gastrointestinal effects from R. communis (vomiting 19.6%, diarrhea 8.9%, nausea 7.9%) and dermal effects from R. pseudoacacia (puncture 28.7%, dermal irritation/pain 27.9%, and edema 13.3%).

CONCLUSIONS

While toxalbumin plant exposures were generally well-tolerated, continued evaluation of risk is warranted since plants were primarily identified by the public. Major effects occurred in under 1% of cases overall, and not at all following unintentional ingestions. These findings should help allay concerns that unintentional ingestions of toxalbumin plants by young children will cause serious toxicity and possibly death.

Multiple tumors of the follicular infundibulum: a cutaneous reaction pattern?

The etiology of tumor of the follicular infundibulum (TFI) is unknown. Eruptive forms of TFI are rare. We present the case of a 49-year-old woman with multiple lesions on the arms, shoulders, trunk, buttocks, and legs of more than 3 years' duration. On clinical and histologic examination, a diagnosis of multiple TFI was made. Additionally, the patient presented with other rare remarkable features including severe pruritus, the Köbner phenomenon, and underlying inflammatory cell infiltration of the tumors. These findings strongly suggest that eruptive TFI may represent a kind of cutaneous reaction.

Sulfur spring dermatitis

Thermal sulfur baths are a form of balneotherapy promoted in many cultures for improvement of skin conditions; however, certain uncommon skin problems may occur after bathing in hot sulfur springs. We report the case of a 65-year-old man who presented with multiple confluent, punched-out, round ulcers with peripheral erythema on the thighs and shins after bathing in a hot sulfur spring. Histopathologic examination revealed homogeneous coagulation necrosis of the epidermis and papillary dermis. Tissue cultures showed no evidence of a microbial infection. The histopathologic findings and clinical course were consistent with a superficial second-degree burn. When patients present with these findings, sulfur spring dermatitis should be considered in the differential diagnosis. Moreover, the patient's clinical history is crucial for correct diagnosis.

Impaired Contact Hypersensitivity Reaction and Reduced Production of Vascular Endothelial Growth Factor in Tumor Necrosis Factor-α Gene-Deficient Mice

Tumor necrosis factor (TNF)-alpha is an important proinflammatory cytokine in contact hypersensitivity (CHS) reactions. Previous efforts to assay CHS in TNF-alpha gene-deficient (-/-) mice have demonstrated a significant reduction in ear skin weight at 24 h following challenge by oxazolone, although the mechanisms of this suppression have not been examined. To further characterize the impaired CHS during evolution of the elicitation phase in TNF-alpha -/- mice and to clarify its mechanisms, focusing on the roles of TNF-alpha and vascular endothelial growth factor (VEGF), we used an established method of CHS assay-sensitization and challenge by trinitrochlorobenzene (TNCB)- in TNF-alpha -/- and wild-type mice. We compared the histopathology of the sequential evolution of CHS between the two groups of mice and assessed both the extent of inflammatory cell infiltration and the degree of dilatation in dermal vessels labeled with CD31. We quantified the production of VEGF in the epidermis at specific time points by using a murine VEGF ELISA kit. The CHS reaction was markedly suppressed in TNF-alpha -/- mice at all time points of the elicitation phase. Histologically, in TNF-alpha -/- mice we observed diminished vascular permeability, reduced numbers of infiltrating inflammatory cells, neutrophils at 12 h, mononuclear cells and eosinophils at 24 h, and a decreased area of dilatation of vessels labeled with CD31. The level of epidermal VEGF in wild type mice increased rapidly after challenge and peaked at 24 h, paralleling the peak of ear swelling. In contrast, the peak level of epidermal VEGF in TNF-alpha -/- mice was significantly reduced. These results suggest that TNF-alpha plays an enhancing role in the elicitation phase of the CHS reaction. Diminished degrees of vascular permeability, dilatation of CD31+ vessels, and inflammatory cell infiltration in TNF-alpha -/- mice are likely to be the result of a lack of TNF-alpha and reduced production of epidermal VEGF.

Enhanced excitability of MRGPRA3- and MRGPRD-positive nociceptors in a model of inflammatory itch and pain

Itch is a common symptom of diseases of the skin but can also accompany diseases of other tissues including the nervous system. Acute itch from chemicals experimentally applied to the skin is initiated and maintained by action potential activity in a subset of nociceptive neurons. But whether these pruriceptive neurons are active or might become intrinsically more excitable under the pathological conditions that produce persistent itch and nociceptive sensations in humans is largely unexplored. Recently, two distinct types of cutaneous nociceptive dorsal root ganglion neurons were identified as responding to pruritic chemicals and playing a role in itch sensation. One expressed the mas-related G-coupled protein receptor MRGPRA3 and the other MRGPRD (MRGPRA3+ and MRGPRD+ neurons, respectively). Here we tested whether these two distinct pruriceptive nociceptors exhibited an enhanced excitability after the development of contact hypersensitivity, an animal model of allergic contact dermatitis, a common pruritic disorder in humans. The characteristics of increased excitability of pruriceptive neurons during this disorder may also pertain to the same types of neurons active in other pruritic diseases or pathologies that affect the nervous system and other tissues or organs. We found that challenging the skin of the calf of the hind paw or the cheek of previously sensitized mice with the hapten, squaric acid dibutyl ester, produced symptoms of contact hypersensitivity including an increase in skin thickness and site-directed spontaneous pain-like (licking or wiping) and itch-like (biting or scratching) behaviours. Ablation of MRGPRA3+ neurons led to a significant reduction in spontaneous scratching of the hapten-challenged nape of the neck of previously sensitized mice. In vivo, electrophysiological recordings revealed that MRGPRA3+ and MRGPRD+ neurons innervating the hapten-challenged skin exhibited a greater incidence of spontaneous activity and/or abnormal after-discharges in response to mechanical and heat stimuli applied to their receptive fields compared with neurons from the vehicle-treated control animals. Whole-cell recordings in vitro showed that both MRGPRA3+ and MRGPRD+ neurons from hapten-challenged mice displayed a significantly more depolarized resting membrane potential, decreased rheobase, and greater number of action potentials at twice rheobase compared with neurons from vehicle controls. These signs of neuronal hyperexcitability were associated with a significant increase in the peak amplitude of tetrodotoxin-sensitive and resistant sodium currents. Thus, the hyperexcitability of MRGPRA3+ and MRGPRD+ neurons, brought about in part by enhanced sodium currents, may contribute to the spontaneous itch- and pain-related behaviours accompanying contact hypersensitivity and/or other inflammatory diseases in humans.

Irritant contact dermatitis

Irritant contact dermatitis (ICD) is the most common form of contact dermatitis. It represents the cutaneous response to the toxic/physical effects of a wide variety of environmental agents. Nowadays, it is recognized that irritancy does not represent a single monomorphous entity but rather a complex biologic syndrome with diverse pathophysiology and clinical manifestations. The clinical presentation is highly variable depending on several factors, including properties and strength of the irritant, dose, duration and frequency of exposure, environmental factors, and skin susceptibility. The pathophysiological mechanism depends on activation of the innate immune system and involves skin barrier disruption, cellular changes, and release of proinflammatory mediators that directly recruit and activate T lymphocytes. The diagnosis of irritant contact dermatitis is often clinical, and involves a comprehensive history and examination, as well as the exclusion of allergic contact dermatitis with patch testing. Recent advances in understanding the pathogenesis as well as better awareness of the clinical significance of ICD will lead to a improved care for our patients.

Contact urticaria and the environment

The environment is defined by the aggregate of surrounding things, conditions, or influences. The biophysical environment includes the physical and biological factors, along with chemical interactions that affect an organism. Contact dermatitis includes any inflammatory skin reaction to direct or indirect contact with noxious agents in the environment. Although the main clinical expression of contact dermatitis is eczema, other expressions like urticaria, contact urticaria (CoU), or lichenoid eruptions are described. The main objective of this chapter is to review CoU, which is often misdiagnosed, as part of the CoU syndrome (CUS).

[The changes of skin barrier of patients with different facial dermatitis and the comparison of CE and KLK5]

OBJECTIVE

To study the clinical symptoms and the condition of skin barrier of different facial dermatitis.

METHODS

The patients with facial dermatitis were divided into 4 groups based on their diagnosis: hormone-dependent dermatitis (HDD) group, sensitive skin (SS) group, cosmetic intolerance (CI) group and normal control group. All patients received the evaluation on clinical symptoms with measuring scale, measurements of stratum corneum water content (SCWC), sebum, pH, trans-epidermal water loss (TEWL) and blood flow. The skin scales were collected for the measurements of the ratio of immature cornified envelope (CE) via immunofluorescence and the concentration of kallikrein 5 (KLK5) via enzyme-linked immunosorbent assay.

RESULTS

There were total 146 patients included (HDD 38, SS 53, CI 15, control group 30), most of them had their symptoms evaluated as moderate to severe. Compared with the control, the disease groups had lower SCWC and sebum (P < 0.05), higher pH, TEWL and blood flow (P < 0.05), higher ratio of immature CE (P = 0.011) and lower concentration of KLK5 (P = 0.000); while these parameters among the disease groups did not show statistical significant difference.

CONCLUSION

There is no difference in the clinical symptoms and the condition of skin barrier between facial dermatitis with different inducements. The growth of CE may be inhibited and the concentration of KLK5 decreases in facial dermatitis.

Molecular allergology in practice: an unusual case of LTP allergy

The authors describe an unusual case of LTP allergy. A 35 years old patient presented repeated episodes of angiooedema after food intake and complained 10 years ago of contact urticaria and rhinoconjunctivitis when exposed to cannabis leaves and to marijuana smoke. The suspected responsible foods, such as wheat flour in bread, are known to contain LTR Oral syndrome occurred after ingestion of walnuts. Cutaneous tests confirmed immediate responses to several flours and nuts and also to cannabis leaf and flower. A few months later he had similar accidents following peach ingestion and drinking of beer and several wines which all induced positive skin tests. Serological investigations using ImmunoCAP and ISAC microarray confirmed IgE positivity for n Pru p3, r Cor a 8 and n Art v3. It was assumed that sensitization to LTP, the major allergen of cannabis, was responsible of the primary sensitization and induced further LTP food allergies.

Allergic contact dermatitis: immune system involvement and distinctive clinical cases

The aim of this review is drawing the attention to the contact dermatitis, an inflammatory skin condition due to pro-inflammatory and toxic factors able to activate the skin innate immunity (irritant contact dermatitis) or caused by a T-cell- mediated hypersensitivity reaction (allergic contact dermatitis). The immune system involvement and a variety of clinical pictures are described in order to better diagnose, prevent and treat allergic contact dermatitis.

[Contact dermatitis and atopic dermatitis--rare comorbidity?]

Allergic contact dermatitis and atopic dermatitis represent two clinical entities resulting from the activation of two mutually exclusive subsets of T lymphocytes. Therefore, one might expect that the ability of atopic patients to evolve allergic contact dermatitis would be diminished. However, results of recent studies indicate, that similar cytokines' spectra play role in the pathogenesis of both diseases. Similarly, the clinical epidemiological studies reveal comparable prevalence rates of contact hypersensitivity in atopic dermatitis patients and in non-atopics patients. Patch testing with contact allergens is substantiated in patients suffering from atopic dermatitis.

Enhanced contact hypersensitivity by delayed T-helper 2 response in BALB/c mice

T-helper (Th) 1/Th2 balance determines the direction of contact hypersensitivity (CHS). To clarify the immunopathogenesis of contact dermatitis, 2,4-dinitrofluorobenzene (DNFB)-induced CHS reaction was compared between the BALB/c and C57BL/6 mice. The two strains were sensitized with DNFB systemically and challenged with DNFB locally. The CHS reaction in BALB/c mice was intense compared with that in C57BL/6 mice at 24 and 48 hours post-DNFB challenge. The dermal lesions were characterized by infiltration of lymphocytes, eosinophils, neutrophils, and macrophages including CD4+ and CD8+ T cells, and interleukin (IL)-4-producing(+) and interferon (IFN)-gamma+ cells in BALB/c mice. In C57BL/6 mice, the composition of inflammatory cells was same as those in BALB/c mice except for eosinophils, CD4+ T cells, and IL-4+ cells. There was no increase in the number of mast cells in the two strains. Local and systemic productions of IL-4 and IFN-gamma in BALB/c mice were higher than those in C57BL/6 mice. Although blood IgE values increased in BALB/c mice, but not in C57BL/6 mice, at 48 hours postchallenge, its value was low. The delayed Th2-like response together with Th1-like response in BALB/c mice may induce strong CHS reaction compared with C57BL/6 mice, which may dominantly develop Th1-like reaction. Moreover, mast cell and IgE do not appear to be involved in delayed CHS.

[Contact sensitivity reaction, its mechanism and regulation]

The contact sensitivity (CS) reaction to haptens is a classical example of cell-mediated immune response. In this reaction, two phases can be distinguished: an early component, detectable as early as 2 hr after subsequent contact with the hapten, and a late component, developing approximately 24 hr after challenge and which is mediated by T cells. In the classical CS reaction, CD4+ T helper 1 (Th1) cells act as effector cells, whereas B-1 lymphocytes supported by NKT cells produce antigen-specific IgM antibodies, which play a crucial role in the initiation of CS. The CS reaction is under the precise control of regulatory circuits. The CS response is negatively regulated by T suppressor (Ts) cells induced by treatment with high doses of antigen. On the other hand, the CS response is positively regulated by T contrasuppressor (Tcs) cells that protect Th1 effector lymphocytes from the action of Ts cells. A new view of a negative regulation of Th1-mediated CS response is based on suppression induced by epicutaneous (e.c.) application of protein antigen. This kind of immunization results in the generation of TCR alphabeta+CD4+CD8+ Ts cells that inhibit the CS response via the released TGF-beta. The suppression induced via e.c. immunization with protein antigen can be abrogated by TCR alphabeta+CD4+ Tcs cells induced by simultaneous exposure to protein antigen and Toll-like receptor (TLR) ligands. This method of e.c.-induced tolerance or its reversal by e.c. application of antigen alone or together with TLR ligands may be effective in new therapeutic strategies because of its effectiveness, ease of induction, and noninvasiveness.

Systemic dermatitis due to tetrazepam

Cutaneous adverse reactions to benzodiazepines seem to be rare. We report a 61-year-old man with adverse reactions after ingestion of metamizole, diclofenac, and tetrazepam. Skin prick tests with metamizole, diclofenac, and tetrazepam were negative. Patch tests with metamizole, diclofenac, and tetrazepam (all at 5% in aqueous solution) were performed, and were positive for tetrazepam. Oral challenge was performed with metamizole, acetylsalicylic acid, diclofenac, and tetrazepam with a positive result for diclofenac and tetrazepam. The patient tolerated other benzodiazepines. We present a patient who can tolerate diazepam but who had a type IV hypersensitivity reaction to tetrazepam confirmed by patch testing and oral challenge. The patient also presented an immediate hypersensitivity reaction after taking diclofenac.

Rapid changes in substance P signaling and neutral endopeptidase induced by skin-scratching stimulation in mice

BACKGROUND

Skin-scratching is a commonly seen behavior in patients with pruritus which sometimes exacerbates original lesions. Substance P (SP) signaling may play a predominant role in the pathophysiology induced by skin-scratching, however, it has not been well-elucidated.

OBJECTIVES

To clarify changes in SP, its receptor NK-1R and a degradating enzyme neutral endopeptidase (NEP) induced by skin-scratching stimulation in mice.

METHODS

After skin-scratching stimulation was given to mice, changes in SP signaling were investigated as follows. Mast cell degranulation was examined with toluidine blue staining. SP-immunoreactive nerve fibers and the expressions of NK-1R and NEP were examined with immunofluorescence. Protein contents of SP and the enzymatic activity of NEP were examined with an ELISA and a colorimetric assay, respectively.

RESULTS

After skin-scratching stimulation, mast cells significantly degranulated within several minutes. SP-immunoreactive nerve fibers disappeared immediately from sensory nerve fibers, indicating the quick secretion and the depletion of SP. Both protein contents of SP and NEP activity in skin decreased dramatically soon after skin-scratching stimulation and thereafter they returned to the basal level within a week. The expression of NK-1R was significantly upregulated in epidermal basal keratinocytes after several days, in which NEP and NK-1R were well-coexpressed. Blocking NK-1R by an NK-1R antagonist suppressed scratching-induced decreases in SP-immunoreactive nerve fibers and in NEP activity.

CONCLUSIONS

The present study clarified changing patterns of factors involved in SP signaling and NEP induced by skin-scratching stimulation. These findings provide basic and useful information to understand the pathophysiology of scratching-associated pruritic skin diseases.

Updates from the British Association of Dermatologists 86th Annual Meeting, 4?7 July 2006, Manchester, U.K

Here we provide a synopsis of the main clinical and research advances in clinical, epidemiological and biological dermatology that were presented at the meeting of the British Association of Dermatologists (BAD) held during 4-7 July 2006, in Manchester, U.K. Only the more important advances or summaries of findings are mentioned. The meeting was held at the Manchester International Conference Centre (Fig. 1). The annual dinner was held at Manchester Town Hall, in the Great Hall decorated with magnificent murals by Ford Madox Brown, with Dr Susan Burge as host.

Functional map and age-related differences in the human face: nonimmunologic contact urticaria induced by hexyl nicotinate

Variation in human skin reactivity to various irritants in association with age and body region has been reported. Hexyl nicotinate (HN), a lipophilic nicotinate ester, was used to induce nonimmunologic contact urticaria in human volunteers of 2 age groups: 10 young subjects [24-34 years, mean +/- standard deviation (SD) 29.8 +/- 3.9 years] and 10 older volunteers (66-83 years, mean +/- SD 73.6 +/- 17.4 years); and to define skin function and potential age-related differences in various facial areas. About 5 mM of HN in ethanol was applied to 8 locations on the face, neck, and volar forearm. A laser Doppler flowmeter was used to determine baseline blood flow and to monitor the skin blood flow changes after HN application. In the contralateral areas, stratum corneum turnover was determined using 5% dansyl chloride in petrolatum. In the young group, the perioral area exhibited the strongest reaction to HN. In the older group, the chin was the most sensitive site. In both the groups, the forearm was the least responsive. The older group demonstrated a stronger reaction than the younger group in 3 sites (forehead, cheek, and nasolabial area). Stratum corneum turnover was slower in the nasolabial area and in the forearm in both age groups, whereas the fastest was in the perioral area and the chin in the younger group and in the chin and the forehead in the older group. Compared to the older group, the younger group showed a slower stratum corneum turnover in the nose and the neck. This study demonstrates the regional and the age-related variability of the stratum corneum turnover and the skin reactions to HN. These observations may help explain some aspects of the cutaneous intolerance in skin care of the face.

Mechanisms of electrode induced injury. Part 1: theory

Electrodes are the essential elements of clinical neurophysiology both in recording of neural activity and in functional electrical stimulation of the nervous system. Therefore it is important to understand the potential complications of using electrodes. In this paper, the factors that influence the chance of electrode related injury are discussed from a theoretical standpoint. The mechanical factors, especially pressure related injury, are discussed first, followed by a discussion of injury that is of chemical origin such as contact dermatitis. Next, the ways in which electrical currents flowing from electrodes can cause injury including: Joule heating, electroporation, electroconformational denaturation, and excitatory neurotoxicity are discussed. The differential effects of constant current and constant voltage stimulation on tissue heating are examined, as are the effects of the conductivity and geometric structure of the stimulated tissue. Finally, the effects of electrochemical reactions are discussed both in the context of surface and implanted electrodes.

[Eczematous skin diseases]

The skin, as one of the most important barriers of the human body, protects the inner homeostasis from the harmful environmental influences as well as physical, chemical and biological factors. When the impact of these factors exceeds the tolerance and reproducing capacity of the skin, pathological alterations will develop. If follows from this that dermatology can surely be considered to be a part of environmental medicine. Eczematous diseases are mostly pathological pictures of varied mechanisms developing as a result of environmental influences (irritants, contact allergens, microbes). Since their clinical appearance is similar, it is a serious professional challenge to diagnose them. In this article we present the clinical features, provoking factors of these skin diseases as well as therapeutical possibilities.

Pimecrolimus and tacrolimus differ in their inhibition of lymphocyte activation during the sensitization phase of contact hypersensitivity

BACKGROUND

As reported previously, oral administration of the calcineurin inhibitors (CNI) pimecrolimus and tacrolimus resulted in equipotent inhibition of the elicitation phase of contact hypersensitivity (CHS) in mice. The sensitization phase was inhibited by tacrolimus but was unaffected by pimecrolimus, even at higher doses.

OBJECTIVE

The kinetics of lymph node hyperplasia and up-regulation of T and B cell activation antigens were analyzed to obtain a better understanding of the divergent CNI profile in CHS.

METHODS

Lymph node (LN) cells of CNI-untreated and treated mice were examined with flow cytometry at various time points after sensitization with oxazolone. LN hyperplasia and drug levels were also determined.

RESULTS

Sensitization induced a higher portion of LN cells expressing the activation antigens CD25, CD69 and CD134 and an increase in activated B cells (B220(+)/CD40(+)) compared to naïve mice. Up-regulation of these markers was completely or profoundly blocked with tacrolimus, whereas pimecrolimus at the three-fold higher dose caused significantly less inhibition. Tacrolimus also completely blocked the sensitization-associated increase of CD11c(+) antigen presenting cells (APC) in LN, whereas pimecrolimus showed significantly less inhibition. In contrast to tacrolimus, LN weight and cellularity were not affected by pimecrolimus at any time point after sensitization. Concentration of tacrolimus in blood and in the draining LN substantially exceeded that of pimecrolimus by factors 6.7-14 and 5.6-5.8, respectively, at the same dose levels.

CONCLUSION

In contrast to tacrolimus, systemic treatment of mice with pimecrolimus only weakly interferes with lymphocyte activation and does not affect hyperplasia of the draining lymph nodes during sensitization.

A Chronic Contact Eczema Impedes Migration of Antigen-Presenting Cells in Alopecia Areata

Long-lasting allergen treatment is the most efficient therapy in alopecia areata (AA). The underlying mechanism is unknown. We here asked whether treatment with a contact sensitizer influences leukocyte migration such that dendritic cell (DC) migration or the recruitment of activated T-cells towards the skin become hampered. Allergen treatment of AA mice was not accompanied by a decrease in skin-infiltrating leukocytes or draining lymph node cells (LNC). However, the distribution of leukocyte subsets was changed with a dominance of monocytes in the skin and a reduced percentage of DCs in draining nodes. Chemokine and chemokine receptor expression in skin and draining nodes was strikingly increased and LNC from untreated and allergen-treated AA mice showed high migratory activity in vitro and readily homed in draining nodes and skin after intravenous injection. However, FITC labelling of the skin and subcutaneous transfer of dye-labelled DC revealed that allergen treatment created a chemokine milieu severely hampering DC migration from the skin towards the draining node. An allergic eczema-induced reduction in DC migration and antigen transfer could well contribute to insufficient T-cell activation and the recovery of hair follicle in AA and possibly be of relevance for other skin-related autoimmune diseases.

The cytokine-dependent MUTZ-3 cell line as an in vitro model for the screening of contact sensitizers

Langerhans cells (LC) are key mediators of contact allergenicity in the skin. However, no in vitro methods exist which are based on the activation process of LC to predict the sensitization potential of chemicals. In this study, we have evaluated the performances of MUTZ-3, a cytokine-dependent human monocytic cell line, in its response to sensitizers. First, we compared undifferentiated MUTZ-3 cells with several standard human cells such as THP-1, KG-1, HL-60, K-562, and U-937 in their response to the strong sensitizer DNCB and the irritant SDS by monitoring the expression levels of HLA-DR, CD54, and CD86 by flow cytometry. Only MUTZ-3 and THP-1 cells show a strong and specific response to sensitizer, while other cell lines showed very variable responses. Then, we tested MUTZ-3 cells against a wider panel of sensitizers and irritants on a broader spectrum of cell surface markers (HLA-DR, CD40, CD54, CD80, CD86, B7-H1, B7-H2, B7-DC). Of these markers, CD86 proved to be the most reliable since it detected all sensitizers, including benzocaine, a classical false negative in local lymph node assay (LLNA) but not irritants. We confirmed the MUTZ-3 response to DNCB by real-time PCR analysis. Taken together, our data suggest that undifferentiated MUTZ-3 cells may represent a valuable in vitro model for the screening of potential sensitizers.

Dissociation between sex differences in the immunological, behavioral, and physiological effects of kappa- and delta-opioids in Fischer rats

RATIONALE

The sex of the individual can have a profound effect on sensitivity to the effects of opioids. Recently, our laboratory provided the first evidence that females may be more sensitive to the immune-altering effects of mu-opioids than males. However, it remains unknown whether kappa- and delta-opioids produce sexually dimorphic effects on immune responses.

OBJECTIVE

The present study sought to determine whether kappa- and delta-opioids produce differential immunological effects in males and females using the memory-T-cell-dependent in vivo inflammatory response contact hypersensitivity (CHS). As sex differences in the magnitude of opioid effects can be outcome-specific, additional experiments were conducted to compare the immunological effects of kappa- and delta-opioids with other behavioral and physiological effects.

MATERIALS AND METHODS

Contact hypersensitivity was induced in male and female Fischer rats. Prior to elicitation of CHS, animals were administered selected doses of the kappa-opioid spiradoline (0.2-20 mg/kg), delta-opioid SNC80 (1-10 mg/kg), or vehicle. The antinociceptive and diuretic effects of spiradoline were also assessed in males and females, as were the locomotor effects of SNC80.

RESULTS

Spiradoline produced significantly greater enhancement of CHS in females than males, but produced comparable antinociceptive and diuretic effects in both sexes. By contrast, SNC80 did not significantly affect the course of CHS in either sex, but females were significantly more sensitive to its locomotor stimulatory effects.

CONCLUSIONS

These results demonstrate that females are more sensitive than males to the CHS-altering effects of spiradoline and that sex differences in the magnitude and direction of opioid-induced sex differences are outcome dependent.

Unexpected effects of UVB in IL-10 transgenic mice: normalization of contact hypersensitivity response

Solar radiation in the UVB range is absorbed primarily by the epidermal DNA where characteristic photodamage results in altered immune responses and mutagenic lesions. UVB exposure of the skin results in a profound upregulation of the anti-inflammatory cytokine, IL-10 and suppression of contact hypersensitivity (CHS). Given that IL-10 is produced after UVB exposure, and that antibodies against IL-10 have been shown to reverse UVB-induced immune suppression, we hypothesized that IL-10 transgenic mice would show an enhanced immune suppression in response to UVB. Using an IL-10 transgenic mouse model (IL-10tg), we examined the CHS response in unexposed animals and those exposed to UVB. Unexposed IL-10tg animals showed a diminished CHS response compared to wild-type. Surprisingly, however, when IL-10tg animals were exposed to UVB, the CHS response was not further suppressed, but rather was restored to the level observed in unexposed wild-type animals.

Predisposition to sensitive skin and atopic eczema

Genes that control the thickness of our skin and its vulnerability to chemicals in the environment play a role in the development of contact dermatitis and atopic eczema. Sensitive skin manifests itself as a burning, stinging or itching sensation following the application of topical products such as soap, bubble baths and cosmetics. The skin may become red and dry after repeated application of these products. New insights into the skin barrier can help us improve treatment of the skin and prevent problems associated with atopic eczema and sensitive skin

Oral tryptic casein hydrolysate enhances phagocytosis by mouse peritoneal and blood phagocytic cells but fails to prevent induced inflammation

Mouse experiments were conducted in order to find whether oral application of tryptic casein hydrolysate (TCH) results in enhancement of phagocytosing capacity of murine phagocytic cells as well as whether such application might be of use for prevention of inflammatory processes. Phagocytosing capacity of phagocytic cells of mice that received oral TCH once daily in a dose of 1.0 mg/g body weight dissolved in 0.5 ml of distilled water for five successive days was significantly higher (p < 0.05) than that of mice given equivalent volumes of distilled water, with a phagocytosing capacity enhancement index being 1.39 and 1.34 regarding peritoneal macrophages and blood phagocytic cells, respectively. Taken on the other hand, the immunostimulatory effects of oral TCH were found to be not enough to prevent mice from inflammation that was induced experimentally using acute (paw edema) and contact hypersensitivity models. A possibility for development of food protein enzymatic hydrolysates as antimicrobial immunostimulants acting through improvement of phagocytic cell functioning is discussed.

Alteration of sensorineural circuits in spinal cord by chronic contact dermatitis

In the present study, eczema-induced alteration of sensorineural circuits of the spinal dorsal horn was investigated. Eczematous lesions resembling atopic dermatitis were induced by repeated application of diphenylcyclopropenone (DCP) onto murine right hind paws. Immunohistochemical labeling of calcitonin gene-related peptide and substance P was increased in the dorsal horn on the DCP-treated side. Expression of calcium binding proteins, calretinin and calbindin-D28K, normally widely seen in dorsal horn interneurons, was up-regulated on the DCP-treated side. E-Cadherin and alpha-N-catenin, synapse-related molecules, were intensely expressed in the spinal dorsal horn of the DCP-treated side. Interestingly, c-Fos positive cells were also significantly increased in laminae I and III of the DCP-treated side. These results suggest an enhanced release of neuropeptides from peripheral afferents and alterations in the sensorineural circuitry of the dorsal horn. These changes may account for the enhanced sensory sensitivity recognized in patients with chronic eczema and atopic dermatitis.

Delayed Inflammatory Reaction to Hyaluronic Acid (Restylane®)

A 45-year-old man received an injection of Restylane (cross-linked hyaluronic acid) to a mid-forehead furrow line in an attempt to reduce its prominence. The injection was uncomplicated and successful in reducing the line. Five months after the injection, he returned with an inflammatory reaction in the area of injection that resolved without treatment over a period of 3 weeks.

Inhibition of scratching behaviour caused by contact dermatitis in histidine decarboxylase gene knockout mice

A neuronal system dedicated to itch consists of primary afferent and spinothalamic projection neurons. Histamine is thought to be one of the main mediators for the transmission of itch sensation. However, there are little available information on the role of histamine in scratching behaviour and sensory transmission of atopic dermatitis and chronic eczema. In the present study, the role of histamine in scratching behaviour and neural conduction of sensation in the chronic eczema model was investigated by using l-histidine decarboxylase (HDC) gene knockout mice lacking histamine. The chronic contact dermatitis was induced with daily application of diphenylcyclopropenone (DCP) on a hind paw of HDC (+/+) and HDC (-/-) mice for 2 months. The observation of scratching behaviour and the hot-plate test were performed in both mice. Histological studies were performed in the skin and spinal cord tissues. Histological examination revealed that both HDC (+/+) and HDC (-/-) mice displayed the similar extent of inflammatory cell infiltration, hyperplastic epidermis and newly spreading of neuronal processes in the skin tissue. Scratching behaviour was exclusively induced in HDC (+/+) mice, whereas it was barely observed in HDC (-/-) mice. The expression of c-Fos was specifically upregulated in HDC (+/+) mice in lamina I of the spinal dorsal horn following repeated DCP application. Scratching behaviour in chronic contact dermatitis in mice was thought mainly mediated with histamine. The afferent pathway of sensation in chronic contact dermatitis model may connect with the central nervous system through lamina I of the spinal dorsal horn.

Visible and subclinical skin changes in male and female dispatch department workers of newspaper printing plants

BACKGROUND AND PROBLEM: Wet work and skin exposure to detergents or solvents are well-established causes of irritant hand dermatitis. In contrast, physical irritation of the skin as another potential cause of occupational hand dermatitis has been investigated less.

MATERIAL AND METHODS

Our study included 71 individuals exposed to physical irritation during work in the dispatch department of two newspaper printing plants. Clinical examination and measurements of transepidermal water loss (TEWL), capacitance and skin surface pH of the skin of hands and forearms was performed.

RESULTS

Erythema and/or scaliness of the hands were unexpectedly common: 26 of the 38 female inlay workers, 11 of the 13 male inlay workers and 15 of the 20 male machine operators were affected, compared to 18 of 28 printers exposed to solvents who had been investigated in a previous study. A significantly higher skin surface pH on the hands (P < 0.05) and, less pronounced, on the forearms (P > 0.05) was found in females. There was no association between domestic skin exposure, according to questionnaire data, and the bioengineering results. Skin cleansing and skin care differed between male and female workers, but were again not associated with the outcomes.

CONCLUSIONS

The point prevalence of skin changes in dispatch department workers in the present study is unexpectedly high, which points to the importance of physical irritation by paper dust. Significant differences in bioengineering parameters between male and female inlay workers were found only for skin surface pH at the exposed back of hands. Future studies should (i) try to elucidate the role of skin surface pH changes and (ii) pay more attention to physical trauma to the skin.

Inducible ablation of mouse Langerhans cells diminishes but fails to abrogate contact hypersensitivity

Langerhans cells (LC) form a unique subset of dendritic cells (DC) in the epidermis but so far their in vivo functions in skin immunity and tolerance could not be determined, in particular in relation to dermal DC (dDC). Here, we exploit a novel diphtheria toxin (DT) receptor (DTR)/DT-based system to achieve inducible ablation of LC without affecting the skin environment. Within 24 h after intra-peritoneal injection of DT into Langerin-DTR mice LC are completely depleted from the epidermis and only begin to return 4 wk later. LC deletion occurs by apoptosis in the absence of inflammation and, in particular, the dDC compartment is not affected. In LC-depleted mice contact hypersensitivity (CHS) responses are significantly decreased, although ear swelling still occurs indicating that dDC can mediate CHS when necessary. Our results establish Langerin-DTR mice as a unique tool to study LC function in the steady state and to explore their relative importance compared with dDC in orchestrating skin immunity and tolerance.

Skin irritation due to repetitive application of adhesive tape: the influence of adhesive strength and seasonal variability

BACKGROUND/PURPOSE

Influence of the repetitive application of pressure-sensitive adhesive tapes on skin was evaluated.

METHODS

Two kinds of tapes with different adhesive strengths were repetitively applied to the inside of the forearm of six volunteers in winter and summer, in order to examine the dermal peeling force, the amount of stripped corneocytes, transepidermal water loss (TEWL), hydration and deepened skin furrows (changes in skin surface topography) in the epidermal stratum corneum.

RESULTS AND CONCLUSION

As adhesive tapes were applied repetitively, dermal peeling force gradually increased while the amount of stripped corneocytes decreased. As the cumulative amount of stripped corneocytes increased with repetitive applications, the skin irritation worsened as measured by increased destruction of the skin surface topography and TEWL. These phenomena were more marked with the stronger adhesive tape, and there was seasonal variability.