**1. Introduction**

The epithelial lining is the first line of defense against the abundance of aggressive factors in the environment. The integer epithelium represents a mechanical barrier, while the physiological processes occurring in and between the cells contribute to dynamic and complex protection from physical, chemical and biological agents. The immune role of the epithelial layer is supported by various cells and cytokines, which show common features between the gastrointestinal tract and the pulmonary and cutaneous systems [1–3]. These similarities in role and functioning have led recent research in the direction of exploring the gut-lung-skin barrier as an entity that not only shows common elements but also interactions [4]. The cross-talk between these three regions refers to various signaling molecules which are mainly involved in local and systemic inflammation [5].

This paper focuses on the roles of cannabinoids in inflammation affecting the gut-lungskin barrier and brings forward the similarities and distinctions in the pathophysiology of the inflammatory conditions affecting these systems. The latest advancements in the

**Citation:** Scheau, C.; Caruntu, C.; Badarau, I.A.; Scheau, A.-E.; Docea, A.O.; Calina, D.; Caruntu, A. Cannabinoids and Inflammations of the Gut-Lung-Skin Barrier. *J. Pers. Med.* **2021**, *11*, 494. https://doi.org/ 10.3390/jpm11060494

Academic Editor: David S. Gibson

Received: 10 April 2021 Accepted: 28 May 2021 Published: 31 May 2021

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field are discussed and supported by the available in vitro and in vivo evidence in the recent literature, as well as the human studies which have been undertaken to validate the effectiveness and safety of cannabinoids in the epithelial inflammation of the gut-lungskin barrier.
