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Background: Acne vulgaris (AV) is a typical inflammation-related condition of the pilosebaceous apparatus that has extremely detrimental impact on one's quality of life & mental health. Interleukin (IL)-36 cytokines (α, β, γ) promote the activation of T-helper 1 and T-helper-17 cells, which then secrete tumor necrosis factor-, interferon-γ, IL-17, IL-22 in addition to other inflammatory mediators. These cytokines stimulate epithelial cells for producing numerous growth factors and inflammatory mediators, thereby exacerbating the inflammation. IL-36 cytokines have been associated with various conditions that are inflammation-related. Aim: Its objective was to evaluate IL-36γ serum levels among AV participants and healthy controls, and to look into any possible connection among IL-36 & the severity of AV. Patients and methods: 45 participants were enrolled in this study after they presented with AV, along with 45 controls who did not have AV. Enzyme-linked immunosorbent assay (ELISA) was utilized to evaluate serum levels of IL-36γ in AV patients and controls. Results: The study revealed that cases with AV had significantly higher IL-36γ serum levels than controls (p < 0.001). IL-36γ serum levels correlated positively with AV severity (P=0.002). Cases with severe acne had higher levels than those with mild & moderate acne (p=0.005). Moreover, IL-36γ serum levels were significantly higher among cases with positive family history of AV (p=0.019). Conclusion: Individuals with AV had significantly greater serum IL-36γ levels in contrast to controls and they were related to AV severity and post acne scarring. IL-36γ may therefore show a significant function in AV inflammatory reactions and the induction of post acne scarring. [ABSTRACT FROM AUTHOR]

Introduction: Adnexal skin tumours are a heterogeneous group of uncommon tumours usually misdiagnosed clinically due to a huge variety of types and their variants. Histopathology usually helps in establishing the diagnosis. The study was conducted to analyse the morphological, clinical and histological features of adnexal tumours (ATs) of the skin at our centre over a period of 5 years. Materials and Methods: A retrospective study was conducted over a period of 5 years (January 2016–January 2021), comprising 85 ATs of skin diagnosed in the Department of Pathology, Sri Devaraj URS Medical College, Kolar, Karnataka, India. All the consecutively reported AT cases were reviewed and reclassified as ATs arising from sebaceous glands, hair follicles or sweat glands. The concordance of clinical and histopathological diagnosis was also assessed. Results: Most of the ATs were benign, with the head and neck being the most common location (61.15%), followed by the trunk (22.3%). Nearly 39% of the tumours were of hair follicle differentiation, 30% sweat gland differentiation and sebaceous gland tumours accounted for 31%. The most common varieties of tumours encountered in the present study included sebaceous cysts and pilomatricoma. The concordance between the clinical and histopathological diagnosis was found to be 50% approximately. Conclusion: Histopathology is the gold standard for diagnosing ATs as they are often misdiagnosed clinically. [ABSTRACT FROM AUTHOR]

Acne vulgaris is a common, inflammatory and multifactorial disease of the pilosebaceous unit that primarily affects adolescents; however, it can be found at any age. When it occurs between birth and 12 years of age it is called pediatric acne, which based on the age at onset has been categorized into neonatal, infantile, middle childhood and preadolescent acne. The importance of this categorization lies in the etiopathogenic processes involved, course, complications and prognosis. Neonatal acne coexisting in the first 8 weeks of life has an excellent prognosis and does not require treatment. Infantile acne occurs from 8 weeks to 1 year; most of them course without complications and have the implication of severe acne in adolescence. Middle childhood acne appears between 1 and 7 years, a period in which there are virtually no adrenal or gonadal hormones, so an underlying endocrinopathy should be investigated. In contrast, preadolescent acne, between 7 and 12 years of age, is very common and considered normal. However, in any patient with symptoms and signs of hyperandrogenism, an endocrinologic disorder should be investigated. Knowledge of childhood acne will allow the treating physician or pediatrician to suspect the existence of an underlying disease. The influence of the Western diet on the severity of acne has been demonstrated and is becoming more relevant. Prompt and effective treatment of acne reduces the psychosocial impact on the patient. However, future research is needed to determine this effect in the pediatric patient. [ABSTRACT FROM AUTHOR]

Sebaceous glands are sebum‐secreting components of pilosebaceous units. The embryological development of the sebaceous gland follows that of the hair follicle and epidermal tissue, beginning between weeks 13 and 16 of fetal development. New sebaceous glands do not normally develop following birth, but their size increases with age. Sebocytes express a multitude of hormone receptors and are heavily regulated to secrete sebum by androgens. There is a large increase of sebum excretion at birth and again at puberty, until approximately age 17. In adulthood, sebum production remains stable and declines to zero in postmenopausal women and in men aged 60‐70. Besides the production and release of sebum, sebaceous glands function to lubricate the skin and hair, provide thermoregulation, and exhibit antimicrobial activity. Research has shown sebaceous glands to possess the cellular capability to transcribe genes necessary for androgen metabolism. Dysfunction of the sebaceous gland can be seen primarily in steatocystoma simplex and multiplex, sebaceous gland hyperplasia, sebaceoma, sebaceous adenoma, sebaceous carcinoma, nevus sebaceus, and folliculosebaceous cystic hamartoma. Sebaceous glands are secondarily involved in acne vulgaris, seborrheic dermatitis, and androgenic alopecia. [ABSTRACT FROM AUTHOR]

In 2018, Schneider and Zouboulis analysed the available tools for studying sebaceous gland pathophysiology in vitro. Since then, the interest in this field remains unbroken, as demonstrated by recent reviews on sebaceous gland physiology, endocrinology and neurobiology, the role of sebaceous glands beyond acne, and several original works on different areas of sebaceous gland function, including sebaceous lipogenesis. Landmark developments in the first part of the 30‐year modelling research dedicated to the sebaceous gland, which is considered by several scientists as the brain of the skin, were the short‐term culture of human sebaceous glands, the culture of human sebaceous gland cells and the development of immortalized sebaceous gland cell lines exhibiting characteristics of normal sebocytes. On the other hand, current developments represent the establishment of sebaceous gland spheroids, the 3D‐SeboSkin model of viable skin explants ex vivo, the combination of culture‐expanded epidermal stem cells of mice and adult humans to form de novo hair follicles and sebaceous glands, when they are transplanted into excisional wounds in mice, and 3D‐printed scaffolds coated with decellularized matrix of adipose‐derived mesenchymal stromal cells and SZ95 sebocytes. These novel tools may become useful platforms for better understanding of cellular and molecular mechanisms governing sebocyte biology and sebaceous gland homeostasis, such as the changes in sebum synthesis and composition, the infundibular differentiation and the influence of the innate immunity and the cutaneous microbiome and for identifying potential therapeutic targets of skin diseases affecting the sebaceous glands. [ABSTRACT FROM AUTHOR]

Background: Basic histological knowledge of the different components of the pilosebaceous unit is important in the pathologic interpretation of hair disorders. Aim and Objectives: Due to paucity of detailed microscopic features and photomicrographs of the pilosebaceous unit (PSU) at one place, this study aimed to review the normal developmental stages and provide microscopic features, along with the photomicrographs of different components of the pilosebaceous unit that could prove useful in certain hair conditions and therapeutic procedures. Materials and Methods: Tissue samples were obtained from the site of experimentally induced incisional and excisional skin wounds in such a way that parts of normal skin around these healing skin wounds were included. These samples were processed for routine paraffin serial sectioning. These sections were stained with routine and special stains. Histological features were recorded under different magnification of the Trinocular microscope. Study Limitation: The study presented is a part of another research study related to skin wound healing in adult albino rats. Results: The general structure of the pilosebaceous unit was shown by routine Haematoxylin and Eosin staining. While the presence and distribution of collagen fibres were demonstrated by Masson's Trichrome and PicroSirius Red with Fast Green staining, type III collagen (reticular) fibres were observed in PicroSirius Red with Silver Nitrate staining and that of elastin fibres were demarcated by Aldehyde Fuchsin with Fast Green staining method. Conclusion: In certain conditions and procedures, such as hair disorders, hair transplantation, and follicular drug delivery, where detailed histology of the pilosebaceous unit is required, the present study wherein many special stains were used could prove very useful for quick and easy identification of different types of cells and fibres associated with the pilosebaceous unit. [ABSTRACT FROM AUTHOR]

The acne disease is a disorder of pilosebaceous units and highly common which is chronic and recurring and is distinguished due to the development of comedones (open and closed) and papules along with the formation of pustules, nodules, and cysts. Acne afflicts adolescent population mostly and adults occasionally with 9.4% global prevalence. The pathogenesis is multifaceted which involves increased androgen production (hyperseborrhea) followed by pilosebaceous unit hyperkeratinization, colonization of Propionibacterium acnes, along with releasing the inflammatory mediators. The key hormones such as androgens, insulin, insulin-like growth factor are responsible for the acne vulgaris progression and contiguous with various mostly preventable and modifiable risk factors, such as environmental factors, genetic predisposition, lifestyle factors and drug use by a successful management. Due to the exceptional patient prerequisites and its complex clinical presentation acne possesses various treatment challenges. There are various treatment options available, but the available guidelines are insufficient to make evidence-based recommendations. The treatment includes topical therapy such as benzoyl peroxide, antibiotics and retinoids, systemic retinoid and antibiotics, hormonal, and various adjuvant treatment modalities like comedo removal, laser, and light therapy intralesional injections and chemical peels. The present review focuses on a general overview of acne vulgaris and its treatment modalities available presently. [ABSTRACT FROM AUTHOR]

Eruptive vellus hair cysts are rare benign tumors of pilosebaceous unit with vellus hairs, which appear in childhood or young adults. Their etio-pathogenesis is poorly known. A review of the literature shows that eruptive vellus hair cysts (EVHC) might be inherited as autosomal dominant or acquired, and might be associated with other genodermatoses like pachyonychia congenita and anhidrotic ectodermal dysplasia. Although it is a benign tumor of pilosebaceous unit, this condition is rather difficult to treat. Here we report a case of 23 years old female with multiple, asymptomatic, slate-grey to bluish papules on face and ears for last 5 years, with a positive family history of similar lesions in other siblings. To the best of our knowledge, this is the first case of autosomal dominant facial variant of eruptive vellus hair cysts to be published from Pakistan. [ABSTRACT FROM AUTHOR]

Background: acne vulgaris is a chronic inflammatory disease of the skin that affects the individuals of all ages, especially adolescents. An association between serum zinc levels and acne vulgaris have been reported in some studies. Objective: the aim of our study was to estimate serum zinc level in patients with acne vulgaris and healthy subjects and its association with severity of disease. Patients and Methods: this study was conducted on 60 patients (subdivided into 4 groups according to severity of disease according to Global Acne Grading System) and 60 normal individuals as a control group. Results: there was highly significantly statistical difference between all patients and control groups as regard serum zinc level (mean of serum zinc level in patients and control groups were 49.85 ±19.61 and 63.46 ± 22.95 respectively, p=<0.001). Conclusion: it is concluded that zinc deficiency in acne patients could be one of the causes of acne and also that zinc levels may not be related to the severity. [ABSTRACT FROM AUTHOR]

The uppermost aspect of the hair follicle, known as the infundibulum or hair canal, provides a passageway for hair shaft egress and sebum secretion. Recent studies have indicated that the infundibulum and sebaceous ducts are lined by molecularly distinct differentiated cells expressing markers including Keratin 79 and Gata6. Here, we ablated Gata6 from the skin and observed dilation of both the hair canal and sebaceous ducts, independent of gender and hair cycle stage. Constitutive loss of Gata6 yielded only a mild delay in depilation‐induced entry into anagen, while unperturbed mutant mice possessed overtly normal skin and hair. Furthermore, we noted that Keratin 79 and Gata6 expression and localization did not depend upon each other. Our findings implicate Gata6 in maintaining the upper hair follicle and suggest that regulation of this transcription factor may be compromised in pathologies such as acne or infundibular cystic diseases that are characterized by abnormal expansion of this follicular domain. [ABSTRACT FROM AUTHOR]

Acne vulgaris (AV) is the familiar chronic skin ailment affecting most of the individuals. This multifarious, disease involves the bacterium gram-positive, anaerobic Propionibacterium acnes (P. acnes) which resides on skin microflora, and participated in acne inflammation and acne lesions. The object of this review is to discuss presently available in vitro, ex vivo, and in vivo models to evaluate the cosmetic formulations that are developed for dealing and prevention of acne formation. These various available models offer new chances for further research on biologically active materials, drugs & pharmaceutical as well as cosmetics for acne treatment. [ABSTRACT FROM AUTHOR]

Abstract: Terence Kealey first pioneered the isolation and organ maintenance of human eccrine and sebaceous glands in the early to mid‐1980. This led to subsequent methods describing the isolation and culture of human hair follicles, the human pilosebaceous unit as well as the sebaceous duct. The importance of these models in the study of the biology of human skin glands and appendages has been demonstrated in numerous publications and their importance as models for animal replacement, refinement and reduction (3Rs) is increasingly important. In particular, in vitro (ex vivo) hair follicle culture has played a significant part in helping elucidate the role of signalling molecules in regulating hair growth and hair fibre formation and has been especially useful in understanding metabolic aspects of hair growth. However, obtaining sufficient numbers of hair follicles is becoming increasingly difficult as plastic surgery becomes less invasive and smaller skin samples provided. There is therefore an urgent requirement for the next generation of in vitro models using cell lines and tissue engineering, and this has led to the development of immortalised cell lines as well as attempts to model hair follicle embryogenesis in vitro and development of skin on a chip. [ABSTRACT FROM AUTHOR]

Introduction: Acne Vulgaris (AV) is a common inflammatory disease of pilosebaceous units. Liver X Receptor-α (LXR-α) is a ligand activated transcription factor. It controls transcription of genes involved in lipid and fatty acid synthesis. Cyclooxygenase 2 (COX2) is a rate limiting enzyme in prostaglandin synthesis. It plays important role in inflammation. Aim: To evaluate the immunohistochemical expression of LXR-α and COX2 in acne vulgaris skin biopsies to explore their possible pathogenic role in this disease. Materials and Methods: Sixty five subjects were included (45 cases with AV and 20 age and gender-matched healthy controls). Skin biopsies were taken from lesional and perilesional skin of cases and from site-matched areas of control subjects. The evaluation of LXR-α and COX2 was done using immunohistochemical technique. Data were collected, tabulated and statistically analysed using a personal computer with "(SPSS) version 11" program. Chi-square test was used to study the association between qualitative variables. Mann- Whitney test was used for comparison between quantitative variables. Student's t-test was used for comparison between two groups having quantitative variables. Spearman's coefficient was used to study the correlation between two different variables. Differences were considered statistically significant with p<0.05. Results: COX2 was upregulated in lesional skin compared with peilesional and control skin both in epidermis and pilosebaceous units (p<0.001 for all). Higher epidermal COX2% was significantly associated with papulopustular acne (p=0.009) and higher acne score (p=0.018). Higher pilosebaceous units COX2% was significantly associated with papulopustular acne (p=0.04). LXR-α was upregulated in lesional skin compared with peilesional and control skin both in epidermis and pilosebaceous units (p<0.001 for all). Higher LXR-α % in epidermis and pilosebaceous units was significantly associated with papulopustular acne (p=0.01 for both) and higher acne score (p=0.03 for both). Significant positive correlation was detected between COX2% and LXR-α % in epidermis (p=0.001, r=0.87) and pilosebaceous units (p=0.001, r=0.65). Conclusion: Both LXR-α and COX-2 play a role in the pathogenesis of acne vulgaris through their effects on cellular proliferation, inflammation and lipid synthesis. Research for new therapeutic modalities based on their inhibition is needed. More understanding of the interaction between LXR-α, COX2 and acne lesions may lead to effective interference, possibly directed toward specific cell types or steps within inflammatory pathways. [ABSTRACT FROM AUTHOR]

Background: Epidermoid cysts, one of the common benign intradermal or subcutaneous tumors commonly result from the trauma to the pilosebaceous unit in the hair bearing area. In areas without hair, these cysts are considered implantation and proliferation of squamous epithelium into the dermis due to injury. Aims: The aim is to evaluate the clinicopathological details with emphasis on unusual findings related to epidermoid cysts. Study Design: This is a retrospective cross-sectional study carried out over 2 years. Materials and Methods: A total of 103 cases of epidermoid cysts were included in the study. The clinical details such as age, gender, sites, and dimensions were noted. The histopathological findings were evaluated and correlated with the clinical findings. Results: The highest incidence was observed in the age group of 21-30 years (23.3%, 24/103) and the most common affected region was the head and neck region (32%, 33/103). The size of cysts ranged from 0.3 to 9 cm in diameter with a mean of 2.1 cm. The unusual sites observed in this study were four at the left sole, two at right sole, two at prepuce, and one each at the right finger, left palm, and oral cavity. Histopathological findings included rupture of epidermoid cysts with giant cell reaction, melanin pigmentation, and association with other pathologies such as keloid and lipoma. Conclusion: Epidermoid cysts are common benign intradermal or subcutaneous tumors, but they can have unusual presentations and histopathological findings. Epidermoid cysts need early diagnosis and treatment as they can cause cosmetic and functional impairment. [ABSTRACT FROM AUTHOR]

Folliculosebaceous Cystic Hamartoma (FSCH) is an uncommon cutaneous hamartomatous lesion. It is basically a tumour like malformations exhibiting abnormal overgrowth of biphasic elements i.e., epithelial and mesenchymal components that are normally found in the skin. Few other hamartomas of pilosebaceous origin are trichofolliculoma, trichodiscoma, fibrofolliculoma and pilar sheath acanthoma. Though distinct, this entity shares similar histological features to Sebaceous Trichofolliculoma (STF). Hence, a proper histological examination is must in differentiating it from STF and other clinical and histological entities. Authors hereby, describes a case of FSCH in a 37-year-old male who presented with a slow growing cystic mass on his left earlobe, an uncommon location for such lesion. The mass was excised, and a detailed histological evaluation showed a characteristic multinodular growth pattern with lobules of pilosebaceous glands forming nodules around cystically dilated follicular infundibular structures. No hair shafts were seen in the cystic cavity ruling out differential diagnosis of sebaceous hyperplasia which could have been a close mimic. The intervening stroma revealed dense collagen, sheets and lobules of adipocytes, many vascular channels filled with fibrinous deposits. Perivascular adipocytes were also noted along with few nerve tissues (perineurium). A detailed clinicopathological work-up helped in arriving at a final diagnosis of FSCH with neural component. The patient was doing well till last six months of follow-up. No recurrence of similar lesion was noted in the patient. [ABSTRACT FROM AUTHOR]

Acne vulgaris is a chronic inflammatory disease with a complex pathogenesis that affects predominantly adolescents. The aim of the study was to investigate the interrelations between the presence of acne and several variables associated with somatic growth, pubertal maturation, and environmental conditions (altitude and regions of residence). A population sample of 6,200 clinically healthy boys (0-19 years) was examined and the presence of acne was determined. Height, weight, testicular volumes, penile length and circumference, as well as pubic hair were also measured. The prevalence of moderate and severe acne in the whole group was 7.74 %, while in the age group 12-19 years, it was 19.31 %. Twelve-15-year-old boys with acne were taller and heavier than the ones without. They also had increased penile length and circumference as well as larger testicular volumes. Somatometric and pubertal characteristics of 17-19-year-old boys with and without acne were similar. The prevalence of the disease did not differ between the rural and urban inhabitants. However, the acne frequency decreased with the increasing of the altitude where the boys lived. Conclusions: Our results showed that the development of acne vulgaris in male adolescents was associated with an intensive growth and pubertal maturation, while obesity per se did not play an important role. Of particular interest was the association between the prevalence of acne and the altitude of residence. [ABSTRACT FROM AUTHOR]

Abstract: Allergic contact dermatitis (ACD) is caused by low-molecular weight compounds called haptens. It has been shown that the potency of haptens can depend on the formulation in which they are applied on the skin. Specifically the sensitization potency of isothiocyanates, a group of haptens which can be released from e.g. adhesive tapes and neoprene materials, increases with the presence of phthalates; however, the underlying mechanisms are not clear. A better understanding of the mechanisms governing the potency of haptens is important, e.g. to improve the risk assessment and the formulation of chemicals in consumer products. In this study we have explored phthalate-induced effects on the sensitization potency, skin distribution, and reactivity of fluorescent model isothiocyanate haptens using non-invasive two-photon microscopy to provide new insights regarding vehicle effects in ACD. The data presented in this paper indicate that the sensitization potency of isothiocyanates increases when applied in combination with dibutylphthalate due to a specific uptake via the pilosebaceous units. The results highlight the importance of shunt pathways when evaluating the bioavailability of skin sensitizers. The findings also indicate that vehicle-dependent hapten reactivity towards stratum corneum proteins regulates the bioavailability, and thus the potency, of skin sensitizers. [Copyright &y& Elsevier]

The current study aimed to deliver minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide; MXD), a potent hypertrichotic agent, into the pilosebaceous units, exploring the potential of the liposomal system. MXD-loaded liposomes of different compositions were prepared by a thin-film hydration technique and subsequently characterized for various vesicle-specific attributes (i.e., size, shape, lamellarity, and entrapment efficiency). Comparative analysis among these compositions was conducted with reference to their vesicle-specific parameters, drug deposition, and drug-delivery mechanism toward pilosebaceous units. The latter may bring about a distinct change in MXD therapy for various aliments related to pilosebaceous units, such as alopecia. The in vitro drug release, ex vivo skin permeation, and drug-retention behavior of the prepared formulation were evaluated by employing rat skin (normal as well as pilosebaceous free) and semipermeable membrane. The results revealed that the neutral liposomes (mean vesicle size, 3.83 ± 0.18 μm) showed maximum drug deposition in the pilosebaceous units among all the other tested formulations. A quantitative estimation of pilosebaceous delivery revealed that the concentration of MXD in each pilosebaceous unit decreased in the following order: neutral liposomal formulation (5.8 × 103 to 7.25 × 103 μg) > positively charged liposomal formulation (4.7 × 103 to 5.87 × 103 μg) > negatively charged liposomal formulation (4.2 × 103 to 5.25 × 103 μg) > nonliposomal formulation (1.6 × 103 to 2.0 × 103 μg). Stability studies construed the need to store the liposomal formulation at lower temperatures. The results of the current work indicate that the neutral liposomes can deliver the drug molecules into pilosebaceous units more effectively than the other studied formulations. [ABSTRACT FROM AUTHOR]

Abstract: The pilosebaceous unit is a complex structure that undergoes a specific growth cycle and comprises a few important drug targeting sites. For example, drugs can be targeted to the bulge region with stem cells or to the sebaceous glands. Interest in pilosebaceous units is directed towards their utilization as reservoirs for localized therapy and also as a transport pathway for systemic drug delivery. Improved investigative methods, such as differential stripping, are being developed in order to determine follicular penetration. This article reviews relevant aspects of effective follicle-targeting formulations and delivery systems as well as the activity status of hair follicles, and variations in follicle size and distribution throughout various body regions. Each of these factors strongly affects follicular permeation. We provide examples of improved penetration of particle-based formulations and of a size-dependent manner of follicular penetration. Contradictions are also discussed, indicating the need for detailed future investigations. [Copyright &y& Elsevier]

Abstract: Acne is a common skin disorder of the pilosebaceous unit. In addition to genetic, hormonal and environmental factors, abnormal colonization by Propionibacterium acnes has been implicated in the occurrence of acne via the induction of inflammatory mediators. To gain more insight into the role that sebocytes play in the innate immune response of the skin, particularly in acne, we compared the antimicrobial peptide and proinflammatory cytokine/chemokine expression at mRNA and protein levels, as well as the viability and differentiation of SZ95 sebocytes in response to co-culture with representative isolates of P. acnes type IA and type IB as well as Escherichia coli-derived lipopolysaccharide (LPS). We found that, in vitro, P. acnes type IA and IB isolates and LPS induced human β-defensin-2 and proinflammatory cytokine/chemokine expression, and influenced sebocyte viability and differentiation. Our results provide evidence that sebocytes are capable of producing proinflammatory cytokines/chemokines and antimicrobial peptides, which may have a role in acne pathogenesis. Furthermore, since P. acnes types IA and IB differentially affect both the differentiation and viability of sebocytes, our data demonstrate that different strains of P. acnes vary in their capacity to stimulate an inflammatory response within the pilosebaceous follicle. [Copyright &y& Elsevier]

The pilosebaceous unit (PSU) response to androgen is variable. Certain population of PSU respond to androgen in a distinctive pattern that results in sexual hair development in some, sebaceous gland development in others. Furthermore, androgen excess is variably manifest in women as hirsutism, acne vulgaris, seborrhea, or pattern alopecia. Although sebaceous cells act as intracrine cells, activating pro-hormones to potent androgens that act within the sebocyte, hair follicle metabolism predominantly inactivates testosterone. Androgen action in the sexual hair follicle appears to be mediated by the dermal papilla and possibly, by inducing expression of a specific keratin, hHa7, in the hair medulla. The data do not clearly support a relationship between idiopathic hirsutism, the hirsutism that occurs in the absence of androgen excess, and variations in androgen mechanism of action. Androgens are prominent among the hormones that modulate the biological mechanism regulating the hair cycle. However, the basis for the variable pattern of PSU response to androgen is unclear, as is the basis for the variable development of hirsutism in response to androgen excess and the incomplete reversal of hirsutism by anti-androgen treatment. Improved treatment of hirsutism awaits improved understanding of the nature of the interaction between androgens and other determinants of hair follicle biology. [ABSTRACT FROM AUTHOR]

We have developed liposomal formulation of 5-aminolevulinic acid (ALA) to enhance topical delivery and examined ALA-induced protoporpyrin (PpIX) expression in rat pilosebaceous unit throughout hair cycle. Two types of liposomes—glycerol dilaulate (GDL) and phosphatidylcholine (PC)—were formulated and both liposomal ALA increased PpIX expression in rat dorsal skin and pilosebaceous units when compared with free ALA. However, iontophoresis combined with liposomal ALA reduced the expression intensity of PpIX in hair bulbs although it achieved deeper and wider expression of PpIX through transfollicular pathway. After topical application in intact or depilated rat skin, liposomal ALA produced excellent PpIX expression in pilosebaceous units. The expression pattern and intensity of PpIX changed in hair cycle-dependent manner: specific expression only in sebaceous glands was observed at telogen; strong expression in whole pilosebaceous units was shown at anagen with intense expressions in hair bulbs and sebaceous glands; and a pattern similar to anagen but reduced intensity in the hair bulbs was seen at catagen. Throughout hair cycle, the expression pattern and intensity were dramatically changed in hair follicular epithelial cells depending on the cell density and proliferation activity of those cells, whereas those were consistent in sebaceous glands regardless of hair cycle. Little expression was shown in dermis. Photoactivation effect of 20% liposomal ALA-PDT using a red filtered-halogen lamp damaged sebaceous glands, hair follicles and epidermal layers. Formation of a thicker epidermal layer was observed, and hair induction after depilation was inhibited along with damage in sebaceous glands. [ABSTRACT FROM AUTHOR]

Modern therapeutic approaches allow to control sebaceous secretion but knowledge about the sebaceous gland and its precise function within the pilosebaceous unit is still insufficient. Steroid hormones are the principal albeit not exclusive regulators of the sebaceous glands. Three phases may be distinguished in sebaceous physiology: secretion-production, stocking in the follicular reservoir, and excretion. Human “native” intracellular sebum, before secretion, is composed of squalene, waxes, and triglycerides. Once secreted, the sebum is colonised by various xenobiots whose development is controlled by several defensive humoral mechanisms and by the contact with ambient oxygen. Oxygen and micro-organisms transform “native” sebum, lysis of triglycerides to fatty acids being the most pronounced activity. Certain components of this complex mixture of molecules present in the sebum are clearly cytotoxic or irritant, provoking reactive follicular hyperkeratosis and comedone formation — the first step to acne. Some lipophilic organisms like Malassezia yeast may be highly antigenic and induce chronic inflammatory reactions like in seborrhoeic dermatitis. Demodex is an intrafollicular parasite feeding on sebum that frequently causes blepharitis. Sebum is also a vehicle transporting and transmitting several endogenous and exogenous molecules, including potential regulatory factors of hair follicles. Recent development of in vitro cultures of functional sebocytes should help to better understand several aspects of the sebaceous gland’s biology. [Copyright &y& Elsevier]

The article presents a study which examines the association of langerhans cells (LCs) with sebaceous glands in murine skin. Findings discussed include the strong immunogenic capacity in vitro of LCS, the relative importance of LCs and dermal dendritic cells and the role of LCs in immune responses involving sebaceous glands.

Skin is innervated by a multitude of sensory nerves that are important to the function of this barrier tissue in homeostasis and injury. The role of innervation and neuromediators has been previously reviewed so here we focus on the role of the transient receptor potential cation channel, subfamily V member 1 (TRPV1) in wound healing, with the intent of targeting it in treatment of non-healing wounds. TRPV1 structure and function as well as the outcomes of TRPV1-targeted therapies utilized in several diseases and tissues are summarized. In skin, keratinocytes, sebocytes, nociceptors, and several immune cells express TRPV1, making it an attractive focus area for treating wounds. Many intrinsic and extrinsic factors confound the function and targeting of TRPV1 and may lead to adverse or off-target effects. Therefore, a better understanding of what is known about the role of TRPV1 in skin and wound healing will inform future therapies to treat impaired and chronic wounds to improve healing. [ABSTRACT FROM AUTHOR]