Skin lipid profiling in normal and seborrhoeic shih tzu dogs

Primary Prevention of Canine Atopic Dermatitis: Breaking the Cycle-A Narrative Review

Canine atopic dermatitis (cAD) is a common and distressing skin condition in dogs, affecting up to 30% of the canine population. It not only impacts their quality of life but also that of their owners. Like human atopic dermatitis (hAD), cAD has a complex pathogenesis, including genetic and environmental factors. Current treatments focus on managing clinical signs, but they can be costly and have limitations. This article emphasizes the importance of preventing cAD from developing in the first place. Understanding the role of the skin's protective barrier is crucial, as its dysfunction plays a vital role in both hAD and cAD. hAD prevention studies have shown promising results in enhancing the skin barrier, but more research is needed to support more robust conclusions. While hAD primary prevention is currently a focal point of intensive investigation in human medicine, research on cAD primary prevention remains under-researched and almost non-existent. Pioneering effective prevention strategies for cAD holds immense potential to enhance the quality of life for both dogs and their owners. Additionally, it bears the promise of a translational impact on human research. Hence, further exploration of this crucial topic is not only relevant but also timely and imperative, warranting support and encouragement.

Performance and Tolerance of a Protocol for Idiopathic Chronic Greasy Seborrhea in 18 Dogs Using a Shampoo and Mousse Containing Plant Extracts

The study aimed to evaluate the tolerance, performance and effect on hair lipids and skin hydration of a protocol combining applications of one shampoo and subsequent mousses containing plant extracts (Ophytrium and Seboliance) in dogs with an undiagnosed chronic greasy keratinisation disorder. Six dogs were washed with plain water on day (D)0. Twelve dogs were shampooed on D0 and received eight mousse applications at 48-72 h intervals from D2 to D18. Clinical score (CS), Natural Moisturizing Factors (NMF) and hair lipids (HL) were evaluated on D0, D0 + 4 h, D7, D14 and D24. At baseline, no significant differences were observed in CS, NMF and HL between groups. In the control group, CS and HL remained stable throughout the study while a slight decrease in NMF was observed at D0 + 4 h. CS was significantly reduced in the test group between D0 and D7 (-53%) which reached 91% at D24 (p < 0.05), with no side effects. NMF levels decreased in the test group at D0 + 4 h (-73%, p < 0.0001) and returned to baseline from D14. In conclusion, one shampoo and subsequent mousse applications rapidly and safely improved coat quality in dogs with an undiagnosed keratinisation disorder without affecting NMF and HL contents over the study period.

Effects of age, sex, and breed on the composition of free extractable ceramides in the stratum corneum of healthy dogs

Ceramide (CER), an important component of the extracellular lamellar lipids in the stratum corneum (SC), plays a critical role in maintaining the cutaneous barrier function. This study aimed to determine whether the quantity of free extractable SC CERs in dogs was affected by the age, sex, or breed. Fifty-eight dogs from the breeds Shiba Inu, beagle, miniature dachshund, shih tzu, and golden retriever, without any history of skin problems, were enrolled in this study. Lipid extracts from the SC were subjected to high-performance thin-layer chromatography to quantify the free extractable CERs. There were weak negative correlations between the age and the amount of free extractable CERs, CER [NP] (non-hydroxy fatty acids linked to phytosphingosines), CER [AS/NH] (α-hydroxy fatty acids linked to sphingosines/non-hydroxy fatty acids linked to 6-hydroxysphingosines), and CER [AP] (α-hydroxy fatty acids and phytosphingosines). There were no significant sex- or breed-related differences in the amounts of free extractable SC CERs in the dogs. These findings imply that aging causes a decline in the amount of free extractable SC CERs in dogs, similar to that observed in humans. The sex or breed of the dogs investigated in this study did not influence the amount of free extractable SC CERs.

Prevalence and Associated Diseases of Seborrheic Skin in Adults

Background

Seborrhea is a skin condition characterized by abundant production of sebum associated with typical dermatological conditions such as rosacea and acne. Little is known about the prevalence of seborrhea and the frequency of concurrent skin diseases in the general population.

Objective

To investigate the epidemiology and comorbidity of seborrhea in the adolescent and adult working population.

Methods

In large-scale examinations by dermatologists in 343 German companies, the seborrheic skin type and the occurrence of skin findings were documented electronically. Odds ratios (OR) and their 95% confidence intervals (95% CI) of further skin diseases were computed. Logistic regression analyses were conducted for each disease using seborrhea as dependent variable.

Results

A total of 48,630 employees were examined. About 6.0% showed seborrhea (6.6% in men, 5.4% in women). Seborrhea strongly predicted acne (OR 3.59; CI 3.18-4.05), trichilemmal cysts (OR 1.99; CI 1.25-3.18) and rosacea (OR 1.45; CI 1.17-1.81). Regression analyses controlling for age, gender and phototype confirmed significant associations of seborrhea with acne and rosacea.

Conclusion

Only a minor proportion of the working population shows meaningful seborrheic skin. However, this condition predicts distinct skin diseases and thus needs attention, in particular, with respect to consulting and secondary prevention.

Establishment and characterization of a canine sebaceous epithelial cell line derived from an eyelid mass

Little is known about the pathological roles of sebaceous glands in canine skin diseases, as most examinations have been conducted with cultured human sebaceous epithelial cell lines. To our knowledge, there is no available canine sebaceous epithelial cell line. The purpose of this study was to establish a canine sebaceous epithelial cell line and characterize it. An eyelid mass in a dog was surgically resected for treatment, and it was histologically diagnosed as sebaceous epithelioma. Collected tissue was conducted for culture, and the growing epithelial-like cells were passaged. The cells showed continuous proliferation for over 6 months. After 40 passages, the cells were named CMG-1. Lipid droplets in the cytoplasm of CMG-1 cells were confirmed by Oil Red O staining. As reported in studies with human sebaceous epithelial cell lines, lipogenesis in CMG-1 cells was promoted by linoleic acid, whereas transforming growth factor-β (TGF-β) suppressed it. Additionally, real-time PCR revealed that the expression levels of chemokines and cytokines, including CC chemokine ligand (CCL)-2, CCL-20, CXCL-10, Tumor necrosis factor-α (TNF-α), Interleukin (IL)-1α, IL-1β, and IL-8, were significantly increased in CMG-1 cells following treatment with lipopolysaccharide. In conclusion, we successfully established a new canine sebaceous epithelial cell line. Our data indicated that lipogenesis and inflammatory responses were quantitatively evaluable in this cell line. CMG-1 cells could be useful for the pathological analysis of sebaceous gland diseases in dogs.

Development of an in vitro submerged culture system to synthesize epidermal ceramides in canine keratinocytes

Ceramides (CERs) in the stratum corneum (SC) are known to play a crucial role in determining skin barrier function in dogs. We aimed to develop an in vitro culture system that synthesized epidermal CER classes to better understand the synthesis of CER classes in canine SC-. Canine keratinocyte cells (MSCEK) at appropriate confluency were incubated with high Ca²⁺ (1.8 mM CaCl₂) supplemented serum-free medium. Eight days post Ca²⁺ application, the surface of cultured MSCEK was broadly stained with anti-loricrin antibody implying that the keratinocytes had stratified into stratum granulosum. MSCEK cells synthesized heterogenous epidermal CERs, similar to those seen during the stratification of canine keratinocytes. CER fractions obtained from MSCEK cells were comparable to those from canine SC, including CER[EOS] (combination of ω-hydroxy fatty acids and sphingosines), CER[NP] (combination of non-hydroxy fatty acids and phytosphingosines), and CER[EOP] (combination of ω-hydroxy fatty acids and phytosphingosines), all of which are lowered in the SC during canine atopic dermatitis. Thus, the present study provides a simple culture system as a tool for in-depth analysis of CER production in canine keratinocytes.

Effects of sphingolipid extracts on the morphological structure and lipid profile in an in vitro model of canine skin

Ceramides (CER) are essential sphingolipids of the stratum corneum (SC) that play an important role in maintaining cutaneous barrier function. Skin barrier defects occur in both human beings and dogs affected with atopic dermatitis, and have been associated with decreased CER concentrations and morphological alterations in the SC. The aim of the present study was to investigate the changes induced by three different sphingolipid extracts (SPE-1, SPE-2 and SPE-3) on the morphological structure and lipid composition of canine skin, using an in vitro model, whereby keratinocytes were seeded onto fibroblast-embedded collagen type I matrix at the air-liquid interface. Cell cultures were supplemented with SPE-1, SPE-2, SPE-3 or vehicle (control) for 14 days. The relative concentrations of lipids were determined by ultra-performance liquid chromatography coupled to mass spectrometry. The ultrastructural morphology of samples was examined by transmission electron microscopy. SPE-1 induced significant elevation in total CERs, CER[NS], CER[NDS], CER[NP], CER[AS], CER[AP], CER[EOS] and CER[EOP] subclasses, whereas SPE-2 induced a significant elevation in total CER, CER[AP] and CER[EOS] compared with control conditions. Ultrastructural analysis revealed an increase in lamellar-lipid structures in the SC of SPE-1-treated samples. The findings demonstrated that SPE-1 stimulates production of CERs, as shown by changes in lipid composition and ultrastructural morphology. Thus, SPE-1 contributes to the formation of a well-organised SC and represents a potential therapeutic target for improving skin barrier function in atopic dermatitis.

Canine epidermal lipid sampling by skin scrub revealed variations between different body sites and normal and atopic dogs

BACKGROUND

Previously, we evaluated a minimally invasive epidermal lipid sampling method called skin scrub, which achieved reproducible and comparable results to skin scraping. The present study aimed at investigating regional variations in canine epidermal lipid composition using the skin scrub technique and its suitability for collecting skin lipids in dogs suffering from certain skin diseases. Eight different body sites (5 highly and 3 lowly predisposed for atopic lesions) were sampled by skin scrub in 8 control dogs with normal skin. Additionally, lesional and non-lesional skin was sampled from 12 atopic dogs and 4 dogs with other skin diseases by skin scrub. Lipid fractions were separated by high performance thin layer chromatography and analysed densitometrically.

RESULTS

No significant differences in total lipid content were found among the body sites tested in the control dogs. However, the pinna, lip and caudal back contained significantly lower concentrations of ceramides, whereas the palmar metacarpus and the axillary region contained significantly higher amounts of ceramides and cholesterol than most other body sites. The amount of total lipids and ceramides including all ceramide classes were significantly lower in both lesional and non-lesional skin of atopic dogs compared to normal skin, with the reduction being more pronounced in lesional skin. The sampling by skin scrub was relatively painless and caused only slight erythema at the sampled areas but no oedema. Histological examinations of skin biopsies at 2 skin scrubbed areas revealed a potential lipid extraction from the transition zone between stratum corneum and granulosum.

CONCLUSIONS

The present study revealed regional variations in the epidermal lipid and ceramide composition in dogs without skin abnormalities but no connection between lipid composition and predilection sites for canine atopic dermatitis lesions. The skin scrub technique proved to be a practicable sampling method for canine epidermal lipids, revealed satisfying results regarding alterations of skin lipid composition in canine atopic dermatitis and might be suitable for epidermal lipid investigations of further canine skin diseases. Although the ceramide composition should be unaffected by the deeper lipid sampling of skin scrub compared to other sampling methods, further studies are required to determine methodological differences.