1. Introduction
Human skin consist of three main layers the outermost epidermis , middle dermis and innermost hypodermis layer that act as physical barrier, provide selective permeation, secretion and excretion. Anatomically epidermis principally comprised of keratinocytes resulting in potent outermost barrier. The skin at surface functions as physical permeability barrier mainly regulated by with particular paracellular junctions situated within in coextensively the hair follicles and inter-follicular epidermis. Underneath it, the underlying provide structural, innervation, support and nourishment while the hypodermis layer performs as an cushioning adipose depot and insulating .Furthermore, secretions from sebaceous glands and sweat promote to the surface lipid film and microecological balance which regulate the transdermal penetration of exogenous agents. Additionally, there is ostensibly a structural obstacle at the epithelial basement layer at the underlying paracellular junction and obstacle in blood vessels and glands. Furthermore , obstacle action in specific skin conditions should be named structural obstacle are often impacted in the duration of cutaneous disorder for instance psoriasis and atopic dermatitis. (Gorzelanny et al., 2020)
Psoriasis is a chronic autoimmune related inflammatory skin disorder, interrelated with clinical complication for instance psoriatic cardiovascular, psychological, arthropathy and diabetes mellitus, hepatic diseases. The predisposing determinant for psoriasis can be categorized into two segment namely intrinsic and extrinsic predisposing determinant. The globally occurrence is roughly 2%, however it varies by regions. It shows that it is less common in african and some asian ethnicities and approximately 11% in Scandinavian and Caucasian ethnicities. Recommended that genetic background,environmental factors and ethnicity impact the emergence of psoriasis. Herediatory factors perform a substantial function in the pathphysiology of psoriasis. Psoriasis vulnerability 1 (PSORS1) is a substantial vulnerable herdiatary unit for psoriasis that is situated internal a 220 kb section of the principally histocompatibility interconnected on chromosome 6p21. In hereditarily predisposed participants, several triggering element can obtain the disorder. Additionally there are well-established management strategies for inflammatory psoriasis disorder namely phototherapy, topical therapy, biological therapy and systemic non-biological therapy it is still difficult to neglect their limitation which include some medications' side effects, limited efficacy and poor solubility. This required that for order to avoid the problem associated with traditional medicine and formulation other, more sophisticated methods has to be found. According to this viewpoint, the idea of nanoparticle (NP) drived therapy has surfaced as a viably way to create tailored drug delivery system for management of inflammatory psoriasis condition. The development of therapeutic agents in liposome and nanocarrier (nanocapsule, nanoparticle, dendrimers and micelles)is the main emphasis of nanotechnology. Nanomaterials constitute effective physiolochemical characteristics that make them highly ideal treatment that promote targeted drug delivery and cellular uptake. Their large surface area and small particle size improve bioavailability, solubility and absorption of poorly water absorbed drug specifically those categorized under class II and IV drugs of biopharmaceutical classification system (BCS). This help to improve target ability, decrease side effects and increase drug efficacy. It is possible that nanoparticle will become more important in pharmaceutical delivery system technology in near future since they have the potential to be used in the diagnosis and management of numerous conditions. The use of nanotechnology in many scientific fields particularly health is expanding and new medication are quickly taking the place of conventional ones. The general anatomy and physiology of skin, psoriasis and nanoparticles technique and recent advancement of disease and clinical trials are all covered in this review. (Yan et al., 2026)
1.1 Pathophysiology of Skin
The integumentary system or skin is recognized as the body’s largest organ making up about 16% of total body mass and spanning nearly 20 square feet. The term originates from the Latin integere, meaning “to cover,” which aptly reflects its role as a. Its thickness, texture and structure vary across different body regions, adapting to specific physiological needs (Mohamed & Hargest, 2022). Because the skin forms the primary boundary between the body and its surroundings, understanding its anatomy and physiological functions is vital—particularly in clinical and surgical discipliness(ANATOMY OF THE SKIN, 2025), (Yan et al., 2026).
On a global scale, skin diseases constitute a significant public health burden, affecting an estimated 30–70% of individuals worldwide (Stefanov & Andonova, 2021). These disorders often stem from infectious microorganisms such as bacteria, fungi, and viruses or from inflammatory and immune-related processes of varying causes. While some are acute and cause temporary irritation and psychological stress, others—like psoriasis, atopic dermatitis, and allergic contact dermatitis—are chronic inflammatory conditions marked by persistent immune activation, T-cell infiltration, and increased cytokine release within affected tissues (Stefanov & Andonova, 2021).
Even with modern advancements in dermatological therapies, treating infectious and chronic dermatoses remains difficult due to factors like microbial resistance, variations in skin barrier function, and individual health conditions. Nevertheless, the skin serves as a valuable route for drug administration, offering localized, non-invasive therapeutic potential. The success of topical treatments depends on accurate diagnosis, appropriate formulation selection, and effective drug delivery methods that facilitate adequate skin penetration and improve overall treatment outcomes The figure representation is illustrated in figure 1 below ( Gorzelanny et al., 2020).
Anatomically, it is divided into three layers: epidermis, dermis and hypodermis.
1.2 Skin Anatomy
Three distinct layers make up the skin from the exterior to the inside
• The epidermis
• The dermis
• The subcutaneous tissue or hypodermis.
Figure 1. Layers of skin.
1.2.1 Epidermis
The epidermis serves as both a physical and biological barrier, protecting the body from harmful microorganisms and external irritants. Its major cell type, the keratinocyte, makes up about 80% of the epidermal cells and originates from the ectodermal layer. As these cells move upward from the basal layer to the skin surface, they undergo keratinization—a transformation involving active synthesis followed by gradual degradation of cellular components. Once they reach the outermost layer (stratum corneum), the keratinocytes are naturally shed through desquamation, completing a renewal cycle of roughly 30 to 40 days. The epidermis is not uniform in structure; its deeper surface forms rete pegs, downward projections that interlock with the dermis, strengthening the connection between the two layers. . The figure representation is illustrated in figure 2 below (Mohamed & Hargest, 2022).
Figure 2: Layers of Dermis
Non-Keratinocyte cells of the epidermis
The superficial includes keratinocytes as well as a number of particular cell types such as melanocytes, langerhans cells and merkel cells, each of which makes a distinct contribution to immunity, pigmentation and sensory functions. (Mohamed & Hargest, 2022).
Melanocytes Cells
Melanocytes are dendritic cells located within the stratum basale and arise embryologically from the neural crest. They produce melanin, the pigment responsible for skin color, through the tyrosinase-catalyzed conversion of tyrosine to dihydroxyphenylalanine (DOPA).Exposure to UVB radiation enhances melanin synthesis,providing a photoprotective effect.The pigment is distributed to surrounding keratinocytes viacytocrine secretion,where keratinocytes engulf the dendritic extensions of melanocytes to acquire melanin granules (Yousef et al., 2024).
Langerhans Cells
Langerhans cells are immune dendritic cells primarily situated in the stratum spinosum, with fewer in the stratum basale .Originating from CD34-positive bone marrow precursors, they are part of the mononuclear phagocyte system and serve as key antigen-presenting cells in the skin. These cells express MHC class I and II molecules, enabling antigen uptake and migration to lymph nodes to activate T cells . Their cytoplasm contains characteristic Birbeck granules—rod-shaped or tennis-racket-like organelles—and lacks tonofilaments and desmosomal attachments, allowing them greater mobility within the epidermis (Mohamed & Hargest, 2022).
Merkel cells
Merkel cells are specialized mechanoreceptors found in the stratum basale, concentrated in regions sensitive to touch such as the fingertips, palms, soles, and oral mucosa. These cells form Merkel cell–neurite complexes, where they connect to keratinocytes through desmosomes and interact with sensory nerve endings to detect light tactile stimuli. The associated axon terminals lose their myelin sheath near the junction and flatten into tactile discs, facilitating precise mechanosensory signal transmission(Yousef et al., 2024).
1.2.2 Dermis
The dermis lies beneath the epidermis and is anchored to it by the basement membrane. It provides the skin with mechanical strength, elasticity, and flexibility, largely due to its dense connective tissue composition. This layer is rich in blood vessels, lymphatics, and sensory nerves, which support both nourishment and thermoregulation ( McKnight et al., 2022, Shah et al., 2024) .
The dermis is divided into two distinct layers:
• Papillary Dermis
The upper, thinner region composed of loose connective tissue containing fine collagen and elastin fibers. It interdigitates with the epidermal ridges, ensuring strong attachment between the two layers and allowing nutrient diffusion (Mohamed & Hargest, 2022).
• Reticular Dermis
The deeper and thicker region, consisting of dense irregular connective tissue with coarse collagen bundles, fibroblasts, mast cells and nerve endings. It also houses larger blood vessels, lymphatics, and smooth muscle fibers that attach to hair follicles and glands, providing structural support and resilience (Mohamed & Hargest, 2022).
Dermal connective tissue is primarily composed of three key fiber types:
• Collagen fibers (≈75%), forming wavy bundles that confer tensile strength.
• Elastin fibers, arranged parallel or oblique to collagen bundles, allowing flexibility and recoil.
• Reticulin fibers, fine collagen fibrils that maintain dermo-epidermal stability.
Resident cells include fibroblasts , responsible for collagen synthesis and mast cells, which release histamine and heparin during inflammatory responses. Histiocytes (dermal macrophages) also contribute to immune defense and tissue remodeling(Shah et al., 2024).
1.2.3 Hypodermis
Beneath the dermis lies the hypodermis, also known as the subcutaneous fascia. This layer consists of adipose tissue lobules, loose connective tissue, and a dense vascular network. It cushions underlying structures, acts as an energy reservoir, and aids in shock absorption and thermal insulation. The thickness of the hypodermis varies across body regions and between individuals, reflecting nutritional and metabolic status (Lotfollahi, 2024, Del Rosso & Kircik, 2025).
1.3 Function of skin
The skin is the primary protective barrier of defense and carries out a number of vital physiological processes such as thermoregulation, preventing transepidermal water loss , maintaining internal homeostasis , sensory perception. Additionally, its complex structure regulating penetration of therapeutic agents and other exogenous substance.Various function of skin as shown in figure 3-
Figure 3: Function of skin
1.4 Skin Disease
The skin is vulnerable to a variety of pathological disorders due to frequent exposure to immunological , microbial and environmental factors.Various dermatological problems are often categorized into disorder and disease according to their pathophysiology and etiology. These anomalies could include inflammatory, infectious , structural, functions,pigmentary and autoimmune alterations.The main categories of skin disease as shown in figure 4.
Figure 4: Skin disease
2 Auto Immune
When the body’s innate immune system is unable to discriminate between themselves and other organisms, it attack healthy cells, tissue and organs resulting in autoimmune condition. It immunological tolerance divisions leads to chronic inflammation which damaged cell and gradually destroys tissues. The onset of these disorders is influenced by a combination of genetic susceptibility, immune system dysfunction and environmental or epigenetic factors. Examples of autoimmune disorders include rheumatoid arthritis, which causes inflammation of the joints; psoriasis, characterized by immune-mediated skin inflammation and excessive keratinocyte proliferation; and systemic lupus erythematosus syndrome (SLE), a chronic inflammatory condition that may impact various organ systems. (Furue et al.,2018)
2.1 Psoriasis
About 2–3% of people worldwide suffer from psoriasis, a chronic immune triggered skin condition. Its prevalence tends to be lower in asian and some african populations but may rise to around 11% among Caucasian and Scandinavian groups. The term psoriasis originates from the Greek word “psora”, meaning “to itch”and was historically mistaken for leprosy until it was clinically differentiated in the 19th century (Trivedi et al.,2016).
Clinically, psoriasis is characterized by recurrent inflammatory episodes that lead to excessive proliferation and abnormal maturation of keratinocytes, producing red, scaly, and thickened plaques. Depending on the extent, severity, and localization of the lesions, it is classified into chronic plaque, guttate, pustular, and erythrodermic forms. Among these, chronic plaque psoriasis (CPP) is the most common variant and typically manifests before the age of 40 (Trivedi et al.,2016).
The pathophysiology of psoriasis results from a multifactorial interaction between genetic susceptibility and environmental triggers including infections, mechanical trauma, certain medications, stress, alcohol consumption and smoking. On a cellular level, the condition involves aberrant immune activation mediated by T-cells, dendritic cells, cytokines, and interleukins (IL-17, IL-23, TNF-α), which collectively promote inflammation and keratinocyte hyperproliferation (Sieminska et al., 2024)
The epidermal regeneration normally takes place every 28-30 days but in psoriasis , the process is reduced 3-5 days, which causes undeveloped keratinocytes to accumulate and dense, itchy plaques to appear. The disease can vary from mild, localized scaling to severe, widespread lesions, often accompanied by psychological distress and social impairment, significantly affecting quality of life (Das et al., 2026).
Although several treatment options exist including topical agents, phototherapy, systemic drugs and biologic therapies none can completely eradicate the disease. Current management strategies focus on suppressing inflammation, modulating immune pathways, and enhancing patient well-being rather than providing a definitive cure (Pradhan et al., 2013).
2.1.1 Type of Psoriasis
Psoriasis is a long term inflamed skin condition caused by immune system with several clinical subgroups. This figure illustrated typical form guttate, plaque, flexural and nail psoriasis as well as severe variants such as pustular and erythrodermic psoriasis. Each categories varies in lesions form, location and intensity of inflammation. Various type of psoriasis of skin as shown in figure 5.
Figure 5: Type of psoriasis
• The Plaque Psoriasis (Vulgaris Psoriasis)
The most prevalent type is distinguished by elevated , erythematous plaques that are covered in scales that are silvery-white. Frequently affects the knees, elbows, lower back and scalp and may cause pruritus or discomfort (Rendon & Schäkel, 2019).
• The Nail Psoriasis
Manifests as nail discoloration, pitting, subungual thickening, onycholysis and crumbling, typically affecting fingernails and toenails with implications for function and appearance. (Trivedi et al., 2016).
• The Guttate Psoriasis
Marked by small, teardrop-shaped erythematous lesions over the trunk, limbs, and scalp, often triggered by streptococcal infections (Rendon & Schäkel, 2019).
• The Flexural Psoriasis ((Inverse Psoriasis)
It visible in skin folds like the armpits, groin, inflammatory areas and beneath the abdomen pannus as smooth, bright red plaques. Accounts for approximately 18% of psoriasis cases (kumar et al., 2016).
• The Erythrodermic Psoriasis
A severe, generalized form with widespread redness, exfoliation, itching, and pain, often triggered by abrupt withdrawal of systemic therapy, impaired thermoregulation and skin barrier function, making it potentially life-threatening (kumar et al., 2016).
• The Pustular Psoriasis
Characterized by raised pustules with sterile fluid, surrounded by inflamed skin. May be localized (e.g., palmoplantar pustulosis, acrodermatitis continua of Hallopeau) or generalized, affecting any body area. Occurs in less than 5% of patients (Rendon & Schäkel, 2019).
• Comorbidities and Systemic Associations
Psoriasis is increasingly recognized as a systemic inflammatory disorder. Patients often present with metabolic syndrome features, including obesity, hyperlipidemia, hypertension, type 2 diabetes, and coronary artery disease. Cardiovascular risks—myocardial infarction, stroke, and CVD-related mortality—are elevated even in mild cases. Disease severity correlates with the prevalence of systemic complications, underscoring the importance of comprehensive patient management (Parisi et al., 2013, Yamazaki. et al. 2021)
• Psoriatic Arthritis and Nail Involvement
Psoriatic inflammation can extend to the joints, leading to psoriatic arthritis (PsA). Skin lesions typically precede joint involvement. PsA affects up to 40% of psoriasis patients with approximately 15% undiagnosed. Clinically,it exhibit oligoarticular or polyarticular patterns of dactylitis and enthesitis. The polyarticular form is frequently linked to nail disease. The polyarticular form is often associated with nail disease. Nail psoriasis affects more than 50% of patients and can be the sole manifestation in 5–10%. Presentation depends on the affected structure:
• Nail matrix: pitting, leukonychia, onychodystrophy.
• Nail bed: onycholysis, splinter hemorrhages, oil-drop discoloration.
Joint instability and nail damage are intimately related as much as 80% of those suffering from PsA have altered nails (Yamazaki. et al. 2021).
• Systemic and Psychological Impact of Psoriasis
Psoriasis is recognized as a systemic inflammatory disorder. The disease burden—including pain, pruritus, bleeding and comorbidities significantly impairs quality of life, comparable to cancer, myocardial infarction, or depression. Patients show higher rates of depression, anxiety and suicidal ideation, although effective psoriasis treatment can improve psychological well-being and reduce anxiety symptoms(Nickoloff et al., 2004)
2.1.2 Etiology and causing agent of Psoriasis
Psoriasis is a multifactorial disorder involving genetic predisposition, environmental triggers and immune dysregulation (Rendon & Schäkel, 2019).
• Genetics Factors
Genetics significantly influence disease susceptibility. About 10% of the population carry psoriasis-related genes, but only 1–3% develop















