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Dermal Hypersensitivity: Immunologic Principles and Current Methods of Assessment
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
Skin possesses cellular structures and physiologic functions that qualify it as a secondary immune organ, both in terms of innate resistance to infections and acquired specific immunity to foreign antigens. The concept of tissue-associated lymphoid tissue (TALT) portrays related immune structures and responses within an organ, and encompasses “skin-associated lymphoid tissue” (SALT).31 This specialized set of lymphoid tissues in the skin accounts for epidermotrophism of sensitized T lymphocytes, antigen presentation by Langerhans’ cells, and actions of other dermal cells that may contribute to skin immunity: mast cells; keratinocytes; and possibly dendritic epidermal cells.
Tumour Immunity, Graft Versus Host Disease and Autoimmune Disease
Published in Jeremy R. Jass, Understanding Pathology, 2020
Anatomical pathologists have long observed and described the presence of inflammatory cells, notably lymphocytes, macrophages and eosinophils, in and around cancers. This finding has been correlated with tumour regression, for example in malignant melanoma, and with improved prognosis. Following Burnet’s pioneering work on immune tolerance (page 85), the immune system came to be regarded not only as a defence against infection but also as a system of immunosurveillance that would detect and eliminate cancer cells before they had a chance to proliferate into a recognisable lesion. This view has been given fresh impetus with the introduction of ‘psychoimmunobiology’. Even if, as appears likely, the function of the immune system can be shown to be influenced by mental state, there is surprisingly little evidence that immune mechanisms can inhibit early cancer development Immunity is deliberately suppressed in patients who have received organ transplants. Such patients are at increased risk of certain cancers (e.g. squamous cell carcinoma of skin and lymphoma), but are not at increased risk of developing any of the common and life-threatening forms of cancer. Ultraviolet radiation is also thought to depress skin immunity locally and perhaps add to skin cancer risk by this mechanism. Cancer is an age-related disease and does not threaten breeding efficiency. Therefore there is no evolutionary pressure to acquire a system of cancer immunosurveillance.
Preclinical and Clinical Safety Assessment of Transdermal and Topical Dermatological Products
Published in Tapash K. Ghosh, Dermal Drug Delivery, 2020
Lindsey C. Yeh, Howard I. Maibach
The skin possesses cellular structures and physiologic functions that qualify it as a secondary immune organ, both in terms of innate resistance to infections and acquired immunity to foreign antigens. The specialized set of tissues in the skin accounts for epidermotrophism of sensitized T lymphocytes, antigen presentation by Langerhans cells, and actions of other dermal cells that may contribute to skin immunity (e.g., mast cells, keratinocytes and possibly dendritic epidermal cells). The distribution of immune phenotypes of lymphocyte subpopulations in normal human skin is defined as the “skin immune system.” The primary role of skin as an immune organ has been well reviewed (Henningsen, 1991).
Epigenetic control of skin immunity
Published in Immunological Medicine, 2023
The skin is an organ that is constantly exposed to external stimuli and functions as the first-line of defense against invasion to initiate immune responses [1]. It maintains homeostasis by rapidly responding to external environmental signals that are sensed by the outermost layer of the skin, the epidermis. Upon receiving external stimuli, epidermal cells are first activated by themselves, and then, activate surrounding epidermal cells and immune cells [2–4]. This strengthens both the structural and immunological barriers of the skin, and preemptively prepares the skin for a putative invasion by external stimuli. The activated epidermal cells and responding immune cells also possess a rapid recovery system that enables a quick return to the steady state after exposure to external stimuli. The plasticity of epidermal and immune cells, which can flexibly shift between steady and activated states, is therefore responsible for the maintenance of skin homeostasis [1,5]. Crosstalk with immune cells is also active in other non-immune skin cells, including fibroblasts, nerve cells, and vascular endothelial cells. Thus, non-immune cells as well as immune cells support skin immunity through the reciprocal production of immune-regulatory factors. Disruption of the appropriate crosstalk between these cells results in prolonged inflammation as well as abnormal activation and differentiation of skin component cells, which may manifest as chronic inflammatory skin diseases, such as psoriasis and atopic dermatitis [1,5].
Diversity of T cells in the skin: Novel insights
Published in International Reviews of Immunology, 2023
Natalija Novak, Leticia Tordesillas, Beatriz Cabanillas
With the growing scientific evidence of the relevant role that different subsets of T cells have in skin inflammation and sensitization to antigens, specific T cell populations are becoming key markers and targets in new therapies that seek to induce an improved regulation of skin immunity. An even deeper understanding of the biology and function of T cells in skin immunity will allow the development of more precise therapies in T cell-mediated skin disorders.
Developing a latent class analysis model to identify at-risk populations among people using medicine without prescription
Published in Expert Review of Clinical Pharmacology, 2020
Praveen Kumar-M, Rahul Mahajan, S Kathirvel, Naveen Hegde, Ashish Kumar Kakkar, Amol N. Patil
The present study was carried out to understand patient’s viewpoints and practice regarding MWP use. Such studies form building blocks for any education intervention program that can benefit the patient or general population so as to enhance healthcare quality in a population. In the present study, highest MWP use was observed for patients with eczema. Mild forms of eczema may be managed with low potency topical corticosteroids or topical calcineurin inhibitors along with emollients and avoidance of allergens. The efficacy of the treatment depends upon the potency of the steroid, dose, area of skin involved, and the application technique[5]]. Incomplete resolution of symptoms with steroid topical medication procured without prescription, may lead to increased application frequency or delay in proper diagnosis further worsening the severity[6]]. Similar misuse of potent and super potent topical steroids were reported by many countries[7–10]]. Saraswat et al. reported local chemist consultation as the most common way to obtain topical MWP in a large multicentric study evaluating 2926 study participant patients[1]]. Present study also observed similar findings further adding a value in exploring the reasons for this kind of behavior for the first time. The results showed that convenience and distance are the most common reasons for seeking topical medications without prescription. Usually the waiting time in the public/government hospitals is long, which compromises daily wages, and promotes absenteeism leaving behind an option of quick chemist consultation which is better than inconvenience caused or the rapid consultation in a private hospital especially in developing countries[11]]. Conclusion can stand as a directive to government and higher health officials to make necessary provisions for even distribution of healthcare facilities given the differential geographic population density. This will shorten the distance between the patient and the healthcare facilities saving them from the wages lost and absenteeism’s[12]]. The current study evaluated topical medication use without prescription beyond topical steroids for the first time in Asian continent region. The findings include 20% of study participants using topical antimicrobials without prescription. The antifungal and antibiotic together formed the group with the highest MWP use. Other topical medications without prescription were steroid and skin lightening agents. Trends of antimicrobial use without prescription were also found in the Middle East[13]], Jordan[14]], Egypt[15]]. The reason according to Jafari et al., for the antimicrobial use without prescription was the previous experience with medication for self or the family member. The indication, severity, and treatment duration may differ for subsequent use of antimicrobial[16]]. This is a serious threat especially in the era of pandemic where drug resistance, sepsis management, and local skin immunity disturbance increase hurdles in the quality healthcare delivery[17]].