ABSTRACT
The skin is the first line of defense of our body, and it is composed of the epidermis and dermis with diverse immune cells. Various in vitro models have been investigated to recapitulate the immunological functions of the skin and to model inflammatory skin diseases. The simplest model is a two-dimensional (2D) co-culture system, which helps understand the direct and indirect cellto-cell interactions between immune and structural cells; however, it has limitations when observing three-dimensional (3D) interactions or reproducing skin barriers. Conversely, 3D skin constructs can mimic the human skin characteristics in terms of epidermal and dermal structures, barrier functions, cell migration, and cell-to-cell interaction in the 3D space. Recently, as the importance of neuro-immune-cutaneous interactions in the inflammatory response is emerging, 3D skin constructs containing both immune cells and neurons are being developed. A microfluidic culture device called “skin-on-a-chip,” which simulates the structures and functions of the human skin with perfusion, was also developed to mimic immune cell migration through the vascular system. This review summarizes the in vitro skin models with immune components, focusing on two highly prevalent chronic inflammatory skin diseases: atopic dermatitis and psoriasis. The development of these models will be valuable in studying the pathophysiology of skin diseases and evaluating the efficacy and toxicity of new drugs.
ABSTRACT
The skin is the first line of defense of our body, and it is composed of the epidermis and dermis with diverse immune cells. Various in vitro models have been investigated to recapitulate the immunological functions of the skin and to model inflammatory skin diseases. The simplest model is a two-dimensional (2D) co-culture system, which helps understand the direct and indirect cellto-cell interactions between immune and structural cells; however, it has limitations when observing three-dimensional (3D) interactions or reproducing skin barriers. Conversely, 3D skin constructs can mimic the human skin characteristics in terms of epidermal and dermal structures, barrier functions, cell migration, and cell-to-cell interaction in the 3D space. Recently, as the importance of neuro-immune-cutaneous interactions in the inflammatory response is emerging, 3D skin constructs containing both immune cells and neurons are being developed. A microfluidic culture device called “skin-on-a-chip,” which simulates the structures and functions of the human skin with perfusion, was also developed to mimic immune cell migration through the vascular system. This review summarizes the in vitro skin models with immune components, focusing on two highly prevalent chronic inflammatory skin diseases: atopic dermatitis and psoriasis. The development of these models will be valuable in studying the pathophysiology of skin diseases and evaluating the efficacy and toxicity of new drugs.
ABSTRACT
INTRODUCTION: Attention-deficit hyperactivity disorder (ADHD) was a newly coined term for a disease that existed prior to its naming in the mid 20th century. The issue about whether ADHD is a new disorder or merely a new name for an existing disorder is still controversial. The authors tried to find the clues to the answer for this question through reviewing historical documents for traces of ADHD. CONTENTS: We could find literatures and medical records that contain possible ADHD symptoms. In particular, in 1845, Heinrich Hoffmann's 'fidgety Philip' or 'Johnny Look-in-the-air' nearly satisfies today's criteria for ADHD. Methylphenidate was approved as a promising chemical for inattention in 1957 before the establishment of the concept of ADHD. In 1968, ADHD was first officially introduced as "Hyperactivity Reaction of Childhood" by DSM-II. In 1980, DSM-III, 'Attention Deficit Disorder (ADD)' was adopted as an official diagnostic term and changed to 'ADHD' since the creation of DSM-III-R in 1987. CONCLUSION: As stated above, ADHD has existed since long ago and became familiar via an advanced diagnostic system and therapeutic options.