Narrow-band UVB-induced externalization of selected nuclear antigens in keratinocytes: implications for lupus erythematosus pathogenesis

Development of bullous systemic lupus erythematosus in patient treated with NB-UVB: A case report and comprehensive review of the literature

Key Clinical Message

The use of phototherapy is highly effective in treating various skin diseases. In this study, the aim is to present vesicular and blister lesions in patients treated with UVB for psoriasis. It is advisable to consider the possibility of BSLE in cases of vesiculobullous lesions following phototherapy, along with other potential diagnoses.

Abstract

Bullous systemic lupus erythematosus (BSLE) is a rare form of cutaneous lupus erythematosus that presents as vesicles and blisters on various parts of the body. The pathological appearance of these lesions often shows subepidermal vesicles with deposits of IgG, IgM, IgA, and complement C3 in granular or linear forms under direct immunofluorescence (DIF) examination. Clinical studies demonstrate the effectiveness of phototherapy in treating various skin conditions. While several studies suggest a correlation between phototherapy and the development of vesiculobullous lesions, most of these reports are related to bullous pemphigoid, with limited research on the occurrence of BSLE following phototherapy. In this case report, vesicular and blistering lesions in a 70-year-old man undergoing UVB treatment for psoriasis are described. Pathological examination confirmed the diagnosis of bullous systemic lupus erythematosus, and the patient experienced significant improvement after treatment with dapsone tablets. A literature review was conducted on the development of vesiculobullous lesions after phototherapy, comparing different approaches presented in previous studies. Our conclusion highlights the importance of considering BSLE as a possible diagnosis in cases of vesiculobullous lesions post-phototherapy, alongside other potential conditions.

Nano-encapsulated anandamide reduces inflammatory cytokines in vitro and lesion severity in a murine model of cutaneous lupus erythematosus

Cutaneous lupus erythematosus (CLE) is a heterogeneous autoimmune skin disease which occurs independently and in conjunction with systemic lupus erythematosus. Drug development for CLE is severely lacking. Anandamide (AEA) is a primary endocannabinoid which exhibits immunomodulatory effects through mixed cannabinoid receptor agonism. We evaluated AEA as topical treatment for CLE and assessed benefits of nanoparticle encapsulation (AEA-NP) on cutaneous drug penetration, delivery and biological activity. Compared to untreated controls, AEA-NP decreased IL-6 and MCP-1 in UVB-stimulated keratinocytes (p < 0.05) in vitro. In BALB/c mice, AEA-NP displayed improved cutaneous penetration, extended release and persistence of AEA in the follicular unit extending to the base after 24 h. Utilizing the MRL-lpr lupus murine model, twice weekly treatment of lesions with topical AEA-NP for 10 weeks led to decreased clinical and histologic lesion scores compared to unencapsulated AEA and untreated controls (p < 0.05). Prophylactic application of AEA-NP to commonly involved areas on MRL-lpr mice similarly resulted in decreased clinical and histologic scores when compared to controls (p < 0.05), and reduced C3 and IBA-1 in lesional tissue (p < 0.05). The demonstrated clinical and immunomodulatory effects of treatment with AEA support its potential as therapy for CLE. This work also suggests that encapsulation of AEA improves penetration and treatment efficacy. Future studies will be conducted to assess full therapeutic potential.

Aberrant inflammasome activation as a driving force of human autoimmune skin disease

Autoimmune skin diseases are understood as conditions in which the adaptive immune system with autoantigen-specific T cells and autoantibody-producing B cells reacting against self-tissues plays a crucial pathogenic role. However, there is increasing evidence that inflammasomes, which are large multiprotein complexes that were first described 20 years ago, contribute to autoimmune disease progression. The inflammasome and its contribution to the bioactivation of interleukins IL-1β and IL-18 play an essential role in combating foreign pathogens or tissue damage, but may also act as a pathogenic driver of myriad chronic inflammatory diseases when dysfunctionally regulated. Inflammasomes containing the NOD-like receptor family members NLRP1 and NLRP3 as well as the AIM2-like receptor family member AIM2 have been increasingly investigated in inflammatory skin conditions. In addition to autoinflammatory diseases, which are often associated with skin involvement, the aberrant activation of the inflammasome has also been implied in autoimmune diseases that can either affect the skin besides other organs such as systemic lupus erythematosus and systemic sclerosis or are isolated to the skin in humans. The latter include, among others, the T-cell mediated disorders vitiligo, alopecia areata, lichen planus and cutaneous lupus erythematosus as well as the autoantibody-driven blistering skin disease bullous pemphigoid. Some diseases are characterized by both autoinflammatory and autoimmune responses such as the chronic inflammatory skin disease psoriasis. Further insights into inflammasome dysregulation and associated pathways as well as their role in forming adaptive immune responses in human autoimmune skin pathology could potentially offer a new field of therapeutic options in the future.

Cutaneous Lupus Erythematosus: An Update on Pathogenesis and Future Therapeutic Directions

Lupus erythematosus comprises a spectrum of autoimmune diseases that may affect various organs (systemic lupus erythematosus [SLE]) or the skin only (cutaneous lupus erythematosus [CLE]). Typical combinations of clinical, histological and serological findings define clinical subtypes of CLE, yet there is high interindividual variation. Skin lesions arise in the course of triggers such as ultraviolet (UV) light exposure, smoking or drugs; keratinocytes, cytotoxic T cells and plasmacytoid dendritic cells (pDCs) establish a self-perpetuating interplay between the innate and adaptive immune system that is pivotal for the pathogenesis of CLE. Therefore, treatment relies on avoidance of triggers and UV protection, topical therapies (glucocorticosteroids, calcineurin inhibitors) and rather unspecific immunosuppressive or immunomodulatory drugs. Yet, the advent of licensed targeted therapies for SLE might also open new perspectives in the management of CLE. The heterogeneity of CLE might be attributable to individual variables and we speculate that the prevailing inflammatory signature defined by either T cells, B cells, pDCs, a strong lesional type I interferon (IFN) response, or combinations of the above might be suitable to predict therapeutic response to targeted treatment. Therefore, pretherapeutic histological assessment of the inflammatory infiltrate could stratify patients with refractory CLE for T-cell-directed therapies (e.g. dapirolizumab pegol), B-cell-directed therapies (e.g. belimumab), pDC-directed therapies (e.g. litifilimab) or IFN-directed therapies (e.g. anifrolumab). Moreover, Janus kinase (JAK) and spleen tyrosine kinase (SYK) inhibitors might broaden the therapeutic armamentarium in the near future. A close interdisciplinary exchange with rheumatologists and nephrologists is mandatory for optimal treatment of lupus patients to define the best therapeutic strategy.

Current Concepts on Pathogenic Mechanisms and Histopathology in Cutaneous Lupus Erythematosus

Cutaneous lupus erythematosus (CLE) is an interferon (IFN)-driven autoimmune disease that may be limited to the skin or can be associated with systemic lupus erythematosus (SLE). CLE occurs in several morphologic subtypes ranging from isolated, disc-shaped plaques to disseminated skin lesions. The typical histopathologic pattern of skin lesions is named interface dermatitis and characterized by a lymphocytic infiltrate and necroptotic keratinocytes at the dermo-epidermal junction. Other histopathologic patterns primarily involve the dermis or subcutis, depending on the subtype. One critical mechanism in CLE is the chronic reactivation of innate and adaptive immune pathways. An important step in this process is the recognition of endogenous nucleic acids released from dying cells by various pattern recognition receptors (PRRs), including Toll-like receptors (TLRs) and other cytosolic receptors. Crucial cells in CLE pathogenesis comprise plasmacytoid dendritic cells (pDCs) as major producers of type I IFN, T cells exerting cytotoxic effects, and B cells, previously believed to contribute via secretion of autoantibodies. However, B cells are increasingly considered to have additional functions, supported by studies finding them to occur in highest numbers in chronic discoid lupus erythematosus (CDLE), a subtype in which autoantibodies are often absent. More precise knowledge of how CLE subtypes differ pathophysiologically may allow a tailored pharmacotherapy in the future, taking into account the specific molecular signature in relation to the morphologic subtype.

Narrow-band phototherapy in the treatment of atopic dermatitis: mechanisms of action, methodology of implementation

Phototherapy is widely used to treat various chronic skin diseases. One of the most effective methods of treatment is narrow-band medium-wave ultraviolet radiation with a wavelength of 311 nm (UVB-311). UVB-311 is used for such immune-mediated diseases as atopic dermatitis, psoriasis, vitiligo, mycosis fungoides and others. Despite the fact that the method was developed more than 30 years ago, the exact mechanism of its therapeutic action remains insufficiently studied. To date, most of the effects of UVB-311 are explained by its effect on the immune cells of the skin. This review examines data on the effects on the main molecular targets, including T-lymphocytes, keratinocytes, Langerhans cells, cytokine profile, epidermal barrier proteins. Data on the features of the pathogenetic effect of UVB-311 on the immune mechanisms of pathogenesis in atopic dermatitis were obtained. The issues of dosing by determining the minimum erythemic dose (MED) or skin phototype, methodology of procedures are discussed. Prospects for further study of photobiological aspects of UVB-311 action are determined.

Mehr als nur der Schmetterling – ein Leitfaden durch die Vielfalt des kutanen Lupus erythematodes

Die vielen klinischen Varianten des kutanen Lupus erythematodes (CLE) können solitär oder im Rahmen eines systemischen Lupus erythematodes (SLE) auftreten, auf dessen Vorkommen regelmäßig gescreent werden muss. Neben dem weiblichen Geschlecht und genetischen Faktoren stellen Sonnenexposition, Rauchen und manche Medikamente Risikofaktoren dar. Die wichtigsten CLE-Formen sind der akut-kutane LE (z. B. Schmetterlingserythem, generalisiert makulopapulös, enoral), der subakut-kutane LE (z. B. anuläre Form) und der chronisch-kutane LE (z. B. vernarbend diskoide Läsionen, Pannikulitis, Chilblain-LE). Die Diagnose beruht vor allem auf der Klinik und der Histopathologie, hinzu kommen autoimmunserologische Befunde und die direkte Immunfluoreszenz. Milde CLE-Formen können lokal therapiert werden. Reicht dies nicht aus, ist neben einem Steroidstoß Hydroxychloroquin die Systemtherapie der Wahl. Erweiterte therapeutische Optionen stellen Methotrexat, Retinoide, Dapson, Mycophenolat Mofetil, Azathioprin, Thalidomid, Belimumab und Rituximab dar. Alle CLE-Therapien sind off-label. Eine Aktualisierung der Impfungen sollte nach Möglichkeit vor Beginn einer Immunsuppression stattfinden. Zur Objektivierung des therapeutischen Ansprechens eines CLE empfiehlt sich das regelmäßige Scoring mittels RCLASI (Revised CLE Disease Area and Severity Index). Präventiv ist Sonnenschutz (Cremen, Kleidung, Reiseziele) von höchster Wichtigkeit, da Sonnenexposition Schübe provozieren kann. Ein LE stellt keine Kontraindikation gegen eine Schwangerschaft (SS) dar, jedoch sollte diese nicht in einem Schub eintreten, da dies das Risiko für Fetus und Mutter erhöht. Therapeutisch kommen während einer SS v. a. Steroide, Hydroxychloroquin, Dapson und Azathioprin in Betracht.

New-generation diagnostics in inflammatory skin diseases: Immunofluorescence and histopathological assessment using ex vivo confocal laser scanning microscopy in cutaneous lupus erythematosus

Ex vivo confocal laser scanning microscopy (CLSM) offers real-time examination of excised tissue in reflectance, fluorescence and digital haematoxylin-eosin (H&E)-like staining modes enabling application of fluorescent-labelled antibodies. We aimed to assess the diagnostic performance of ex vivo CLSM in identifying histopathological features and lupus band test in cutaneous lupus erythematosus (CLE) with comparison to conventional histopathology and direct immunofluorescence (DIF). A total of 72 sections of 18 CLE patients were stained with acridine orange (AO), anti-IgG, anti-IgM and anti-IgA; 21 control samples were stained with AO. Subsequently, ex vivo CLSM examination of all samples was performed in reflectance, fluorescence and digital H&E-like staining modes. Superficial and deep perivascular inflammatory infiltration (94.4%), interface dermatitis (88.9%), spongiosis (83.3%) and vacuolar degeneration (77.7%) were the most common features detected with ex vivo CLSM. Kappa test revealed a level of agreement ranging within "perfect" to "good" between ex vivo CLSM and conventional histopathology. ROC analysis showed that the combination of perivascular infiltration, interface dermatitis and spongiosis detected by ex vivo CLSM has the potential to distinguish between CLE and controls. Basement membrane immunoreactivity with IgG, IgM and IgA was identified in 88.8% (n = 15), 55.5% (n = 10) and 55.5% (n = 10) of the CLE samples using ex vivo CLSM, respectively, whereas DIF showed IgG, IgM and IgA positivity in 94.4% (n = 17), 100% (n = 18) and 88.9% (n = 16) of patients, respectively. In conclusion, ex vivo CLSM enables simultaneous histopathological and immunofluorescence examination in CLE showing a high agreement with conventional histopathology, albeit with a lower performance than conventional DIF.

Cutaneous lupus erythematosus: new insights into pathogenesis and therapeutic strategies

Cutaneous lupus erythematosus (CLE) is an autoimmune disease that can present as an isolated skin disease or as a manifestation within the spectrum of systemic lupus erythematosus. The clinical spectrum of CLE is broad, ranging from isolated discoid plaques to widespread skin lesions. Histologically, skin lesions present as interface dermatitis (inflammation of the skin mediated by anti-epidermal responses), which is orchestrated by type I and type III interferon-regulated cytokines and chemokines. Both innate and adaptive immune pathways are strongly activated in the formation of skin lesions owing to continuous re-activation of innate pathways via pattern recognition receptors (PRRs). These insights into the molecular pathogenesis of skin lesions in CLE have improved our understanding of the mechanisms underlying established therapies and have triggered the development of targeted treatment strategies that focus on immune cells (for example, B cells, T cells or plasmacytoid dendritic cells), as well as immune response pathways (for example, PRR signalling, Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signalling and nuclear factor-κB signalling) and their cytokines and chemokines (for example, type I interferons, CXC-chemokine ligand 10 (CXCL10), IL-6 and IL-12).

A review of cutaneous lupus erythematosus: improving outcomes with a multidisciplinary approach

Cutaneous lupus erythematosus encompasses a spectrum of cutaneous disease with different phenotypes, and it potentially intersects with many disciplines in medicine. This review examines the epidemiology, clinical subtypes, pathology, psychology and intervention options for this disorder. It is important to understand the psychological distress that cutaneous lupus can cause and if needed actively investigate this possibility with the patient. Careful liaison between disciplines will achieve the optimum outcome.

NB-UVB irradiation downregulates keratin-17 expression in keratinocytes by inhibiting the ERK1/2 and STAT3 signaling pathways

Keratin-17 (K17) is a cytoskeletal protein produced by keratinocytes (KCs), which is overexpressed in psoriasis and may play a pivotal role in its pathogenesis. Narrow-band ultraviolet B (NB-UVB) irradiation is used as a general treatment for psoriasis, although its impact on K17 expression has yet to be determined. In this study, we aimed to investigate the effect of NB-UVB irradiation on K17 expression and its signaling pathways. After exposure to NB-UVB irradiation, immortalized human keratinocytes (HaCaT cells) were analyzed by flow cytometry, CCK-8 assays and transmission electron microscopy to examine proliferation. Meanwhile, K17 expression in primary human epithelial keratinocytes was detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis and immunofluorescence. HaCaT cells pre-incubated with PD-98059 and piceatannol were subjected to western blot analysis to examine ERK1/2 and STAT3 phosphorylation. The ears of mice treated with imiquimod (IMQ) and irradiated by NB-UVB were taken to examine K17 expression by qRT-PCR, western blot analysis, and immunofluorescence. Our results showed that 400 mJ/cm² of NB-UVB irradiation was the maximum tolerable dose for HaCaT cells and could cause inhibited HaCaT cell proliferation and moderate increase of the early apoptosis. Furthermore, NB-UVB irradiation could downregulate K17 expression by inhibiting the ERK1/2 and STAT3 signaling pathways. In experiments conducted in vivo, NB-UVB irradiation with doses of MED or higher could eliminate the IMQ-induced psoriasis-like dermatitis and inhibit K17 expression. These results indicated that NB-UVB irradiation may eliminate chronic psoriatic plaques by suppressing K17 expression via the ERK1/2 and STAT3 signaling pathways.

How stress contributes to autoimmunity-lessons from Sjögren's syndrome

A large body of clinical evidence on the association between stressful life events and autoimmune diseases suggests that stress may play an important role in the pathogenesis of these disorders. In this article, we discuss the effects of stress, not on the immune system but on specific cell populations against which the autoimmune reactivity is directed. Using Sjögren's syndrome as a model autoimmune disease, we review the role of stress in the initiation and perpetuation of autoimmune reactivity. We present data that reveal the effects of stress on salivary gland epithelial cells, suggesting that stress can become immunogenic through its various effects on salivary gland epithelium.

The deposition of anti-DNA IgG contributes to the development of cutaneous lupus erythematosus

Anti-DNA IgG is a hallmark of systemic lupus erythematosus and induces internal injuries in patients. It is known that cutaneous lupus erythematosus (CLE) involves the deposition of autoantibodies in the dermoepidermal junction of the skin and that anti-DNA IgG binds specifically to keratinocytes. However, the definite role of anti-DNA IgG in CLE remains unclear. The purpose of this study was to elucidate the effect of anti-DNA IgG on keratinocytes in CLE. Skin tissues were collected from patients with CLE and healthy controls. Also, murine anti-DNA IgG was incubated with frozen sections of murine skin or PAM212 keratinocytes. The chemotaxis of J774.2 macrophages was evaluated in special chambers with keratinocytes under anti-DNA IgG stimulation. Enzyme-linked immunosorbent assay, flow cytometry, Western blot, and surface plasmon resonance were used to quantitate the interaction between anti-DNA IgG and keratinocyte-related self-antigens. The results showed that anti-DNA IgG could be eluted from the lesional tissues of CLE patients, depending on the serum positivity. Murine anti-DNA IgG bound preferably to the dermoepidermal zones of normal skin and specifically to collagen III and the suppressor of cytokine signalling 1 (SOCS1) but not to Ro52. Moreover, the chemotaxis of macrophages was promoted by the incubation of anti-DNA IgG with keratinocytes. Interestingly, anti-DNA IgG exaggerated both the expression and the activation of fibroblast growth factor inducible 14 (Fn14) in keratinocytes and regulated SOCS1 signals in a time-dependent manner. In conclusion, anti-DNA IgG may contribute to the development of CLE through binding to keratinocyte-related antigens, exacerbating inflammatory infiltration, and modulating Fn14 and SOCS1 pathways.

Evaluation of UV radiation-induced toxicity and biophysical changes in various skin cells with photo-shielding molecules

Examining the real-time morphological, biophysical, and biomechanical changes associated with skin cell degeneration induced by UVR to understand the mechanisms.

Effects of narrow band UVB (311 nm) irradiation on epidermal cells

Ultraviolet radiation (UVR) is known to be one of the most important environmental hazards acting on the skin. It was revealed that chronic exposure to UVR accelerates skin aging, induces immunosuppression and may lead to the development of skin cancers. On the other hand, UVR has been shown to be effective in the treatment of numerous skin diseases and thus, various phototherapy modalities have been developed to date. Narrow-band ultraviolet B (NB-UVB) emitting a light with a peak around 311 nm has been demonstrated to be effective in the treatment of various skin disorders; currently it is one of the most commonly used phototherapy devices. Despite NB-UVB has been developed more than 30 years ago, the exact mechanism of its therapeutic action remains poorly understood. To date, most of NB-UVB effects were attributed to its influence on immune cells; however, nearly 90% of NB-UVB irradiation is absorbed by epidermis and keratinocytes seem to be important players in mediating NB-UVB biological activity. Here, we have reviewed the current data about the influence of NB-UVB on epidermal cells, with a special emphasis on cell proliferation and death.

Immunologic and genetic considerations of cutaneous lupus erythematosus: a comprehensive review

Cutaneous lupus erythematosus (CLE) refers to those subtypes of lupus erythematosus (LE) that have predominantly skin manifestations. Discoid lupus erythematosus (DLE), subacute cutaneous lupus erythematosus (SCLE), LE panniculitis (LEP) and lupus erythematosus tumidus (LET) all fall into the category of CLE. The pathogenesis of CLE is likely multifactorial. UV irradiation has been shown to induce keratinocyte apoptosis. Impaired clearance of apoptotic cells is a potential mechanism for the development of CLE. UV irradiation can also induce externalization of autoantigens such as Ro/SSA, exposing them to circulating autoantibodies. Some drugs have been associated with CLE. Possible mechanisms include stimulation of an immune response through disruption of central tolerance and altered T cell function. T17 cells may also play a role in the pathogenesis of CLE as they have been detected in skin lesions of LE. Treg cells have been found to be decreased in LE lesions, which may contribute to the breakdown of self-tolerance. Epidermal Langerhans cells are reduced in CLE while plasmacytoid DCs are increased in the lesions of CLE, suggesting that DCs may also play an important role in the pathogenesis of CLE. Type I IFN- and TNF-α are both upregulated in lesions of CLE. Other cytokines such as IL-6 and IL-17 are also implicated in the pathogenesis of CLE. Cellular and cytokine networks can be impacted by environmental factors and genetic variations and this can result in an increased risk of developing autoimmune diseases such as CLE.

Glyphosate-induced stiffening of HaCaT keratinocytes, a Peak Force Tapping study on living cells

The skin is the first physiological barrier, with a complex constitution, that provides defensive functions against multiple physical and chemical aggressions. Glyphosate is an extensively used herbicide that has been shown to increase the risk of cancer. Moreover there is increasing evidence suggesting that the mechanical phenotype plays an important role in malignant transformation. Atomic force microscopy (AFM) has emerged within the last decade as a powerful tool for providing a nanometer-scale resolution imaging of biological samples. Peak Force Tapping (PFT) is a newly released AFM-based investigation technique allowing extraction of chemical and mechanical properties from a wide range of samples at a relatively high speed and a high resolution. The present work uses the PFT technology to investigate HaCaT keratinocytes, a human epidermal cell line, and offers an original approach to study chemically-induced changes in the cellular mechanical properties under near-physiological conditions. These experiments indicate glyphosate induces cell membrane stiffening, and the appearance of cytoskeleton structures at a subcellular level, for low cytotoxic concentrations whereas cells exposed to IC50 (inhibitory concentration 50%) treatment exhibit control-like mechanical behavior despite obvious membrane damages. Quercetin, a well-known antioxidant, reverses the glyphosate-induced mechanical phenotype.

The autoimmune tautology: an in silico approach

There is genetic evidence of similarities and differences among autoimmune diseases (AIDs) that warrants looking at a general panorama of what has been published. Thus, our aim was to determine the main shared genes and to what extent they contribute to building clusters of AIDs. We combined a text-mining approach to build clusters of genetic concept profiles (GCPs) from the literature in MedLine with knowledge of protein-protein interactions to confirm if genes in GCP encode proteins that truly interact. We found three clusters in which the genes with the highest contribution encoded proteins that showed strong and specific interactions. After projecting the AIDs on a plane, two clusters could be discerned: Sjögren's syndrome-systemic lupus erythematosus, and autoimmune thyroid disease-type1 diabetes-rheumatoid arthritis. Our results support the common origin of AIDs and the role of genes involved in apoptosis such as CTLA4, FASLG, and IL10.

The lupus band test in systemic lupus erythematosus patients

The lupus band test (LBT) is a diagnostic procedure that is used to detect deposits of immunoglobulins and complement components along the dermoepidermal junction in patients with lupus erythematosus (LE). The LBT is positive in about 70%–80% of sun-exposed non-lesional skin specimens obtained from patients with systemic LE (SLE), and in about 55% of SLE cases if sun-protected nonlesional skin is analyzed. In patients with cutaneous LE only, the lesional skin usually shows a positive LBT. The LBT helps in differentiating LE from other similar skin conditions and may also be helpful in making the diagnosis of SLE in subjects with no specific cutaneous lesions. Furthermore, a positive LBT may be applied as a prognostic parameter for LE patients. However, the correct interpretation of this test requires detailed knowledge of the site of the biopsy, deposit components, morphology and brightness of the immunofluorescent band, and other associated serologic findings, as well as the response to treatment. It must be emphasized that LBT is a laboratory procedure that should always be interpreted in conjunction with clinical findings and other serological and immunopathological parameters.

Lipidome of narrow-band ultraviolet B irradiated keratinocytes shows apoptotic hallmarks

BACKGROUND

UV light triggers a variety of biological responses in irradiated keratinocytes that might be associated with global perturbation of their lipidome. However, lipids that are specifically affected and the exact molecular mechanisms involved remain poorly understood.

OBJECTIVES

To characterize time-dependent changes of the lipidome of cultured keratinocytes induced by narrow-band ultraviolet B (NB-UVB) irradiation.

METHODS

Immortalized human keratinocytes (HaCaT) were cultured under standard conditions, irradiated with NB-UVB light (311 nm) at 400 and 800 mJ/cm(2) and collected 1, 2, 3, 6, 12 and 24 h later for lipid extraction. Lipid extracts were separated on silica plates in chloroform/ethanol/water/triethylamine (35:40:9:35) and in n-hexane/ethylacetate (5:1) followed by quantitative shotgun lipidomics analysis.

RESULTS

Irradiation with 800 mJ/cm(2) of NB-UVB altered morphology and lipidome composition of HaCaT cells. Ceramide content increased two-fold 6- and 12-h postirradiation with 800 mJ/cm(2), followed by threefold increase in triacylglycerols (TAGs) that peaked at 24 h. In addition, we observed marked increase of various phosphatidylcholine and phosphatidylethanolamine ethers, whereas phosphatidylcholine-species with short-chain fatty acid moieties decreased. The abundance of other lipid species was altered to lesser extent or remained unchanged.

CONCLUSIONS

NB-UVB affected the cellular lipidome of keratinocytes in strictly apoptosis-specific manner.

Morphological damages of a glyphosate-treated human keratinocyte cell line revealed by a micro- to nanoscale microscopic investigation

Among the molecules to which the human skin is exposed, glyphosate is used as an herbicide. Glyphosate has been shown to induce in vitro cutaneous cytotoxic effects, concomitant with oxidative disorders. In this following study, we focused on dynamic events of the loss of HaCaT cell integrity appearing after a glyphosate treatment. In these conditions, we showed that glyphosate is able to disrupt HaCaT cells and to induce intracellular oxidative cascade. In this aim, we optimized the conditions of cell treatment playing on exposure time (from 24 h to 30 min), which directly modify the cell viability profile (glyphosate 50% inhibition concentration from 28 to 53 mM) and allow to track cells along the treatment as an "induction and visualization" process. The combination of atomic force and fluorescence microscopic approaches offered opportunities to lead in parallel an investigation of the membrane surface and of the intracellular disorders, through cytoskeleton, nuclear, and oxidative stress marker targeting. The originality of our approach relies on monitoring all events derived from oxidative stress in process and performed by simultaneous cytotoxic induction and nanoscale cell visualization. We revealed a transition from spread and globular to elongated cell morphology, with a drastic cell size reduction, after a dose- and time-dependent glyphosate treatment; a redistribution of cell surface protrusions was also pointed out. All these membrane damages, added to observations of disorganized cytoskeleton, condensed chromatin, and overproduction of oxidative reactive species, lead us to conclude that glyphosate acts in induction of apoptotic process.