The Imbalance of MMP-2/TIMP-2 and MMP-9/TIMP-1 Contributes to Collagen Deposition Disorder in Diabetic Non-Injured Skin

The importance of the early diagnosis and treatment of diabetes and its cutaneous complications has become increasingly recognized. When diabetic non-injured skin was stained with Masson’s trichrome, its dermal collagen was found to be disordered, its density was variable, and it was dispersed or arranged in vague fascicles. The collagen type I sequencing results of RNA sequencing-based transcriptome analysis of three primary human skin cell types—dermal fibroblasts, dermal microvascular endothelial cells, and epidermal keratinocytes—under high glucose were analyzed. The results showed that both COL1A1 and COL1A2 mRNA expressions were reduced in human dermal fibroblasts (HDFs). The ratio of matrix metalloproteinase (MMP)-2/tissue inhibitors of metalloproteinase (TIMP)-2 and MMP-9/TIMP-1 in HDFs increased when treated with high glucose. By inhibiting MMP-2 and MMP-9 with SB-3CT, collagen deposition disorder of the skin in streptozotocin-induced diabetes mice was alleviated. The imbalance of MMP2/TIMP2 and MMP9/TIMP1 contributes to the non-injured skin disorder of collagen deposition in diabetes, suggesting a possibility for early treatment of diabetes skin complications.

Hollow polydopamine nanoparticles loading with peptide RL-QN15: a new pro-regenerative therapeutic agent for skin wounds

Background Although the treatments of skin wounds have greatly improved with the increase in therapeutic methods and agents, available interventions still cannot meet the current clinical needs. Therefore, the development of new pro-regenerative therapies remains urgent. Owing to their unique characteristics, both nanomaterials and peptides have provided novel clues for the development of pro-regenerative agents, however, more efforts were still be awaited and anticipated. Results In the current research, Hollow polydopamine (HPDA) nanoparticles were synthesized and HPDA nanoparticles loading with RL-QN15 (HPDAlR) that was an amphibian-derived peptide with obvious prohealing activities were prepared successfully. The characterization, biodistribution and clearance of both HPDA nanoparticles and HPDAlR were evaluated, the loading efficiency of HPDA against RL-QN15 and the slow-releasing rate of RL-QN15 from HPDAlR were also determined. Our results showed that both HPDA nanoparticles and HPDAlR exerted no obvious toxicity against keratinocyte, macrophage and mice, and HPDA nanoparticles showed no prohealing potency in vivo and in vitro. Interestingly, HPDAlR significantly enhanced the ability of RL-QN15 to accelerate the healing of scratch of keratinocytes and selectively modulate the release of healing-involved cytokines from macrophages. More importantly, in comparison with RL-QN15, by evaluating on animal models of full-thickness injured skin wounds in mice and oral ulcers in rats, HPDAlR showed significant increasing in the pro-regenerative potency of 50 and 10 times, respectively. Moreover, HPDAlR also enhanced the prohealing efficiency of peptide RL-QN15 against skin scald in mice and full-thickness injured wounds in swine. Conclusions HPDA obviously enhanced the pro-regenerative potency of RL-QN15 in vitro and in vivo, hence HPDAlR exhibited great potential in the development of therapeutics for skin wound healing. Graphic Abstract

​Dermal Response to Experimental Orfvirus (ORFV) Infection in Goats, Mice and Rabbit

Background: During a study on the outbreak of orf in goats, it was intended to study the disease transmissibility in different hosts from field samples and ascertain the infective potential of the agent in laboratory animals compared to goats. Methods: Cutaneous clinical materials from orf virus (ORFV) infected goats was used to experimentally infect naive goats, rabbits and mice and ascertain its infective potential and transmissibility in different hosts. The processed inoculum was applied topically to mimic a natural transmission through injured skin. Regular skin biopsies were taken that revealed characteristic macroscopic and microscopic lesions typical of orf. Result: Virus inoculum applied on abraded skin in goats successfully established the lesions of orf. A parallel inoculation in rabbit and mice could not successfully reproduce the disease in these unnatural hosts beyond a subtle vesicular stage on 3 dpi with subsequent healing by 7 dpi. The lesions in goats regressed spontaneously by 28 days post-infection (dpi). Intracytoplasmic inclusions were associated only in the vesicular stage. Immunopathological progression was observed by immunoperoxidase staining of CD4+ and CD8+ T-cells which were found to appear by day 5 in the dermis and became more abundant and distributed by day 8, but subsequently reduced in number by 15 dpi. CD4+ cells were found to be more numerous and widespread. Viral antigen in tissues could be demonstrated by 4 dpi by immunohistological methods that increased in signal intensity progressively and disappear by 28 dpi. Similarly, viral nucleic acid in the skin could be detected on day 8 dpi but not on 28 dpi by PCR. The present experiment depicts the ease of disease transmissibility through traumatized skin in the primary hosts, but establishment in unnatural hosts may not be readily achieved. The infection was self-limiting with possibly no virus latency as indicated by immunofluorescence and PCR studies.

34 Rete Ridges are Decreased in Dyschromic Burn Hypertrophic Scar: A Histological Study

Introduction Dyschromic hypertrophic scar (HTS) with areas of hyper- and hypo-pigmentation is a common sequelae of burn injury. The mechanism behind the development of dyschromia has not been elucidated. In this study, we provide a histological analysis of these scars with a focus on rete ridge presence. Rete ridges occur in epithelial tissues such as oral mucosa and skin and can be described as undulating “pegs” that are interdigitated with dermal papillae. Rete ridges enhance adhesion of the epidermis to the dermis. We hypothesize that rete ridge presence is important for normal skin physiology, and their absence or presence may hold mechanistic significance in post-burn HTS dyschromia. Methods Subjects with post-burn dyschromic HTS were consented and enrolled (n=27). Punch biopsies of hyper-, hypo-, and normally pigmented scar and skin were collected and stored in formalin. Biopsies were paraffin embedded, sectioned, stained with H&E, and imaged. The number of rete ridges were investigated by calculating a rete ridge ratio from the length of the basement membrane and the length of the epidermis. Results The patient population was predominantly female (55.5%), black (70.4%), and had Fitzpatrick skin Type V (51.9%). The injuries were primarily as a result of flame (37%) and scald (33.3%) and resulted in a median TBSA burn of 7%. The median age of the scar at the time of sample acquisition was 12.2 months. The rete ridge ratio of normally pigmented, un-injured skin was above 1 (1.31 ± 0.04), indicating that normal skin’s basement membrane is longer than its epidermal length due to the presence of rete ridges. HTSs resulting from burn wounds that healed without split thickness autografts were first investigated. The number of rete ridges was higher in normal skin compared to HTS that was either hypo- or hyperpigmented (1.31 ± 0.04 vs. 1.13 ± 0.05 and 1.14 ± 0.04 vs, p< 0.05). This difference was similar despite pigmentation phenotype. When hyper-pigmented scars resulting from wounds that were treated with split thickness autografts (Hyper(+)) were investigated, rete ridge number was significantly higher than in Hyper(-) (1.89 ± 0.23, p< 0.01). Patient age showed a weak correlation (R=-0.33) with rete ridge ratio where older patients had lower rete ridge ratios in normal, un-injured skin. Hyper(+) showed a weak correlation between rete ridge ratio and age of scar (R=-0.38). Conclusions Post-burn HTS that is dyschromic has fewer rete ridges than normal skin. This finding may explain the decreased epidermal barrier function that is associated with HTS.

Local effect of melatonin in an original dermal film limiting lipid peroxidation and accelerating healing in experimental thermal trauma

Разработка и патогенетическое обоснование новых подходов к локальной терапии термической травмы (ТТ) является актуальной и востребованной проблемой. В частности, представляет интерес разработка дермальных пленок (ДП), содержащих эндогенные регуляторы гомеостаза мультитропного действия. Цель исследования - оценка эффекта мелатонина (МТ) в составе оригинальной ДП на процессы репарации и содержание продуктов перекисного окисления липидов (ПОЛ) в коже очага повреждения при локальной термической травме. Методика. Эксперимент выполнен на 126 крысах-самцах Wistar. ТТ ІІІА степени площадью 3,5% моделировали погружением участка межлопаточной области кожи в очищенную воду с температурой 98-99 ºС на 12 с. МТ в составе ДП (0,005 г/г) на основе натрия карбоксиметилцеллюлозы наносили ежедневно после ТТ в течение 5 сут. На 5-е и 10-е сут после ТТ оценивали макроскопическую картину, площадь и глубину ожоговой раны, скорость ее эпителизации. Содержание продуктов ПОЛ в гомогенате кожи ожоговой раны определяли экстрационно-спектрофотометрическим методом в гептановой и изопропанольной фазах липидного экстракта. Результаты. Установлено, что накопление вторичных и конечных продуктов ПОЛ в гептановой и изопропанольной фазах липидного экстракта на 5-е и 10-е сут ассоциировано с площадью ожога. Применение оригинальной ДП с мелатонином приводит к снижению абсолютной и относительной площади ожога, увеличению скорости эпителизации ожоговой поверхности. На 5-е сут обнаружено снижение содержания вторичных и конечных продуктов ПОЛ в изопропанольной фазе, на 10-е сутки - снижение вторичных продуктов ПОЛ в гептановой фазе, конечных продуктов ПОЛ в изопропанольной фазе липидного экстракта. Заключение. Полученные результаты демонстрируют ускоряющий репарацию кожи в очаге ТТ эффект МТ в составе дермальной пленки за счет его ПОЛ-ограничивающего действия, расширяют представления о мультитропных эффектах МТ в организме и являются предпосылкой для применения ДП с МТ в клинической практике. Background. Development and pathogenetic justification of new approaches for local therapy of thermal trauma (TT) is a relevant and in-demand issue. Of special interest are dermal films (DF) containing endogenous pleiotropic regulators of homeostasis. Melatonin (MT) is one of such regulators that is suggested to be protective in TT. The aim of this study was to evaluate the effect of MT in the original DF on indexes of repair and concentration of lipid peroxidation (LPO) products in the injured skin after experimental TT. Methods. Experiments were performed on 126 Wistar male rats. Grade IIIA TT with an area of 3.5% was modeled by immersing a section of interscapular skin in purified water at a temperature of 98-99oC for 12 s. MT formulated into DF (0.005 g/g) based on sodium carboxymethylcellulose was applied after TT daily for 5 days. The macroscopic picture, area and depth of the burn wound, and the wound epithelization rate were evaluated on days 5 and 10 after TT. Concentration of LPO products in the injured skin homogenate was measured by extraction spectrophotometry in heptane and isopropanol phases of the lipid extract. Results. The accumulation of secondary and final LPO products in the heptane and isopropanol phases of the lipid extract on days 5 and 10 was associated with the burn area. The use of the original DF with MT resulted in a decrease in the absolute and relative areas of the burn and an increase in the rate of burn surface epithelialization. On day 5, a decrease in the content of secondary and final LPO products in the isopropanol phase was observed, and on day 10 decreases in secondary peroxidation products in the heptane phase and end LPO products in the isopropanol phase were detected. Conclusion. The results of this study demonstrated that MT formulated into DF accelerates skin repair in the TT focus due to its LPO-limiting effect, expands the understanding of MT pleiotropic effect, and represents a prerequisite for the clinical use of DF with MT.

Protective effect of Luteolin on atopic dermatitis murine model via IgE mediated immune response

Atopic dermatitis (AD) is a serious inflammatory condition associated with severe itching and persistent eczematous lesion. Therefore, the present study was intended to scrutinize the beneficial effect of Luteolin (LT) on the atopic dermatitis murine model. The effect of LT was investigated on the various parameters, such as oxidative stress and inflammation after induction of AD. The serum level of IgE, and cells of the WBC family (neutrophils, basophils, eosinophils, monocytes, lymphocytes, and total WBC) and histopathological analysis of skin tissue were also examined to confirm the effect of LT. Results of the study suggested that LT significantly inhibited the elevated IgE level together with improvement in injured skin tissue architecture. It also reduces oxidative stress (MDA, SOD, and GSH) and inflammation (IL-1β, IL-6, TNF-α, IFN-γ, IL-4, and IL-17A) as evidenced by ELISA analysis. The level of examined WBC family cells was found reduced significantly as compared to the AD model group. In western blot analysis, LT showed significant down-regulation of NF-ĸB and TLR-4. Collectively, our results suggest that LT can effectively reverse the effect of atopic dermatitis via improving immunological response.