Effect of urea-extracted sericin on melanogenesis: potential applications in post-inflammatory hyperpigmentation

BACKGROUND: Hyperpigmentation disorders such as post-inflammatory hyperpigmentation are major concerns not only in light-skinned people but also in Asian populations with darker skin. The anti-tyrosinase and immunomodulatory effects of sericin have been known for decades. However, the therapeutic effects of sericin on hyperpigmentation disorders have not been well documented. METHODS: In this study, we used an in vitro model to study the anti-tyrosinase, tolerogenic, and anti-melanogenic effects of sericin on Staphylococcus aureus peptidoglycan (PEG)-stimulated melanocytes, dendritic cells (DCs), and artificial skin (MelanoDerm™). Enzyme-linked immunosorbent assay, conventional and immunolabeled electron microscopy, and histopathological studies were performed. RESULTS: The results revealed that urea-extracted sericin has strong anti-tyrosinase properties as shown by a reduction of tyrosinase activity in melanin pigments both 48 h and 10 days after allergic induction with PEG. Anti-inflammatory cytokines including interleukin (IL)-4, IL-10, and transforming growth factor-p were upregulated upon sericin treatment (10, 20, and 50 µg/mL), whereas production of allergic chemokines, CCL8 and CCL18, by DCs was diminished 48 h after allergic induction with PEG. Moreover, sericin lowered the expression of micropthalmia-associated transcription factor (MITF), a marker of melanogenesis regulation, in melanocytes and keratinocytes, which contributed to the reduction of melanin size and the magnitude of melanin deposition. However, sericin had no effect on melanin transport between melanocytes and keratinocytes, as demonstrated by a high retention of cytoskeletal components. CONCLUSION: In summary, sericin suppresses melanogenesis by inhibition of tyrosinase activity, reduction of inflammation and allergy, and modulation of MITF function.

The reduction of serum aminotransferase levels is proportional to the decline of the glomerular filtration rate in patients with chronic kidney disease

OBJECTIVE: This study sought to determine the serum aminotransferase levels of patients with predialysis chronic kidney disease and establish their relationships with serum creatinine levels and glomerular filtration rate. METHODS: Patients with chronic kidney disease were evaluated between September 2011 and May 2012. Aminotransferase and creatinine serum levels were measured using an automated kinetic method, and glomerular filtration rates were estimated using the Cockroft-Gault and Modification of Diet in Renal Disease formulas to classify patients into chronic kidney disease stages. RESULTS: Exactly 142 patients were evaluated (mean age: 64±16 years). The mean creatinine serum level and glomerular filtration rate were 3.3±1.2 mg/dL and 29.1±13 mL/min/1.73 m2, respectively. Patients were distributed according to their chronic kidney disease stages as follows: 3 (2.1%) patients were Stage 2; 54 (38%) were Stage 3; 70 (49.3%) were Stage 4; and 15 (10.5%) were Stage 5. The mean aspartate aminotransferase and alanine aminotransferase serum levels showed a reduction in proportion to the increase in creatinine levels (p=0.001 and p=0.05, respectively) and the decrease in glomerular filtration rate (p=0.007 and p=0.028, respectively). Alanine aminotransferase and aspartate aminotransferase serum levels tended to be higher among patients classified as stage 2 or 3 compared with those classified as stage 4 or 5 (p=0.08 and p=0.06, respectively). CONCLUSIONS: The aspartate aminotransferase and alanine aminotransferase serum levels of patients with predialysis chronic kidney disease decreased in proportion to the progression of the disease; they were negatively correlated with creatinine levels and directly correlated with glomerular filtration rate. .

Scanning electron microscopy of acantholysis in pemphigus foliaceus / Microscopia eletrônica de varredura da acantólise no pênfigo foliáceo

We performed scanning electron microscopy of an inverted blister roof in a case of pemphigus foliaceus. The loss of intercellular adherence could be easily seen with low magnification. The acantholytic keratinocytes displayed an irregular and sometimes polygonal contour. Round cells, typically seen in light microscopy, were also observed. The examination of a blister roof allows ultrastructural documentation of the acantholytic changes.

Realizamos microscopia eletrônica de varredura do teto invertido de uma bolha de um caso de pênfigo foliáceo. Com pequeno aumento, a perda da adesão intercelular pôde ser vista claramente. Os queratinócitos acantolíticos demostraram um contorno irregular, algumas vezes poligonal. Células arredondadas, como vistas tipicamente na microscopia óptica, também foram observadas. O exame de um teto de bolha permite uma documentação ultraestrutural das alterações acantolíticas.

Ultrastructural evaluation of human keratinocyte growth and differentiation on a fibrin substrate / Avaliação ultraestrutural do crescimento e da diferenciação de queratinócitos sobre um substrato de fibrina

PURPOSE: In order to circumvent several difficulties that have been met in the routine use of the in vitro keratinocyte cultures using the standard procedure described by Rheinwald and Green, and obtain a more resilient and the least possible immunogeneic skin substitute for a future clinical application, this work studied a new keratinocyte culture system, which envisages the utilization of a fibrin substrate in association with high densities of human keratinocytes. METHODS: Through light and transmission electron microscopy and immunohistochemical assays, long-term proliferative and differentiative characteristics of keratinocytes cultured onto a fibrin gel under immerse and air-liquid interface culture conditions were evaluated. RESULTS: Despite the absence of a dermal substitute, the results demonstrated that the proposed composite was constituted of a transparent and elastic fibrin film covered by a well-attached, multistratified epithelium with morphological characteristics that resemble human epidermis, including the neoformation, albeit incomplete, of the basement membrane. CONCLUSIONS: Increased mechanical resistance due to the presence of an easy handling substrate, the delivery of nonclonfluent keratinocytes as well as the removal of animal-derived cells from the culture system suggest its potential use for future transplantation purposes.

OBJETIVO: Com o intuito de contornar diversas dificuldades encontradas no uso rotineiro de queratinócitos cultivados in vitro pela técnica descrita por Rheinwald e Green, e obter um substituto cutâneo mais resistente e o menos imunogênico possível para futuras aplicações clínicas, este trabalho avaliou um novo sistema de cultura de queratinócitos que prevê a utilização de um substrato de fibrina em associação com queratinócitos humanos em alta densidade. MÉTODOS: Através de microscopia óptica e eletrônica e análise imunohistoquímica, foram avaliadas as características proliferativas e de diferenciação em longo prazo de queratinócitos cultivados em condição imersa e na interface ar-líquido. RESULTADOS: Apesar da ausência de um substituto dérmico, foi demonstrado que o composto proposto constituiu-se de um substrato de fibrina transparente e elástico coberto por epitélio multi-estratificado, bem aderido, com características morfológicas semelhantes à epiderme humana, incluindo a neo-formação, embora incompleta, da membrana basal. CONCLUSÕES: A maior resistência mecânica com a presença de um substrato de fácil manuseio, a possível liberação de queratinócitos não-confluentes, e a remoção de células com origem animal dos sistemas de cultura sugerem que o composto proposto neste estudo apresenta grande potencial para uso clínico futuro.

ultrastructural study of epidermal-melanin unit in vitiligo

The use of electron microscopy to define the cellular changes in vitiligo might prove to be a useful investigative procedure to clarify the pathogenic mechanism of this disease. Examination of vitiligenous skin taken from the margin and center of the depigmented lesions revealed ultrastructural changes in the form of cytoplasmic vacuoles in basal and suprabasal keratinocytes and deposits of extra-cellular granular material in between the keratinocytes in lower epidermis. Melanocytes and melanosomes were completely absent, while Langerhans' cells showed highly vacuolated cytoplasm. There was marked increased in degenerated Langerhans' cells in the center of the vitiligenous lesions. It seems logical to propose that degenerative changes in vitiligo do not only involve the melanocytes, but also keratinocytes and Langerhans' cells i.e. the whole epidermal- melanin unit

Nucleolar organizer regions in a model of cell hyperactivity and regression

Nucleolar organizer regions stained with colloidal silver techniques (AgNOR) evidence sites of active rRNA transcription. It has been proved that AgNOR undergo a rise in number and variations in size and shape in conditions which traditionally involve enhanced cell proliferation and rRNA transcription. AgNOR have been described as a marker of malignant transformation in multiple entities. Our laboratory has previously described their value as markers of radioinduced damage. The finding, at light microscopy level, that silver staining persisted at later post-irradiation times when cells are characteristically inactive, prompted the present study to correlate findings at light microscopy level with the ultrastructural analysis of nucleoli and their AgNOR in a model of irradiated skin. We herein attempt to explain the biological significance of AgNOR variations in the different phases of radioinduced response (which involves cellular hyperactivity followed by regressive features). Ten Wistar rats were submitted to local irradiation of the left leg (the shielded right leg was used as control) with 50 Gy x rays and killed 15 days post- irradiation. Silver staining was performed on ultrathin sections. In the basal layer of control epithelium silver affinity was established for fibrillar centers (FC) and fibrillar dense components (DFC). During the phase of radioinduced hyperplasia (1-3 days post-exposure) basal cells exhibit large reticular nucleoli, with irregular contours and silver staining on DFC. In the regressive phase (4-5 days post-irradiation) silver staining persists despite the halt in transcriptional activity, associated to homogeneous and compact nucleoli. These findings suggest caution in the interpretation of silver staining patterns.

Ultrastructure of the Merkel corpuscles of the lower lip mucosa inferior del mono cebus apella

Se estudió la ultraestructura de los corpúsculos de Merkel en la mucosa del labio inferior del labio de los monos Cebus apella. Las células de Merkel se localizan en la base de la red epitelial adyacente e intimamente asociada con una o dos terminaciones nerviosas intra-epiteliales. Las células de Merkel poseen un núcleo dentado, caracterizado por la concentración de numerosos gránulos denso-teñidos con un rango que varía de 30 a 80 nm de diámetro. Las protrusiones citoplasmáticas de las células de Merkel se extienden en los espacios intercelulares, conteniendo microfilamentos paralelos orientados longitudinalmente. Se observan uniones tipo desmosomas entre el axón terminal y las células de Merkel y queratinocitos adyacentes. El axón terminal muestra la presencia de numerosas mitocondrias y vesículas claras que miden de 30 a 50 nm de diámetro. Nuestros hallazgos sugieren que la protrusión citoplasmática puede servir para detectar el movimiento de queratinocitos adyacentes y también relaciona la capa epitelial con el tejido conectivo de la lámina basal

Hipomelanosis de Ito: estudio con microscopía electrónica / Hypomelanosis of Ito: study with electronic microscopy

Se presenta un niño de 10 años de edad con lesiones musculosas dispuestas en arabescos y arremolinadas en tórax; lineales en miembros superiores e inferiores. Esta coexisten con afectación de SNC y compromiso óseo, dentario y ocular, constituyendo el cuadro de Hipomelanosis de Ito. Se efectúa microscopía electrónica para confirmar el diagnóstico. Se hace referencia a características clínicas y evolutivas, puntualizando las diferencias con otros síntomas neurocutáneos