The increased number and activity of MCs and M2 may implicate inflammation in the fibrotic process in KD. The distinct KD-associated lymphoid aggregate resembles MALT, for which we propose the term 'keloid-associated lymphoid tissue' (KALT). It may perpetuate inflammatory stimuli that promote KD growth. KALT, MCs and M2 are promising novel targets for future KD therapy.

Keloid disease (KD) is a common fibroproliferative disorder of unknown aetiopathogenesis, with highly unsatisfactory treatment. Therefore, it is crucial to have a robust and clinically relevant model for studying KD pathobiology as well as preclinical testing of potential KD therapeutics. However, the unique occurrence of KD in human skin and the corresponding lack of animal models pose a major challenge in KD research. Therefore, we developed a simplified assay for the serum-free, long-term organ culture of KD tissue that facilitates quantitative analyses of major KD read-out parameters. Four millimetre KD punches embedded in a collagen matrix and organ-cultured at the epidermis air-liquid interphase (ALI) in supplemented William's E medium showed optimal tissue, cell and RNA preservation for up to 6 weeks (as measured by H & E and Pyronin Y histochemistry as well as by MTT assay, lactate dehydrogenase release and quantitative Ki67 ⁄ TUNEL immunohistomorphometry). The keloid phenotype persisted well during this period, as shown by collagen-I and -III synthesis (Herovici's histochemistry staining and ELISA), and analysis of the expression of significant KD markers (CD3, CD20, CD31, CD34, CD56, tryptase, Langerin, vimentin, neutrophil elastase, CTGF and Collagen). To functionally evaluate whether this assay can test the response to candidate therapeutics, dexamethasone, a glucocorticosteroid often used in KD therapy, was administered. Indeed, dexamethasone significantly reduced the keloid volume and cellularity plus induced epidermal shrinkage. Therefore, this novel assay provides a quantitative, clinically relevant model system for studying KD pathobiology and response to treatment.Key words: Dulbecco's modified Eagle's medium (DMEM) -enzyme linked immunosorbent assay (ELISA) -keloid disease -organ cultureterminal deoxynucleotide transferase-mediated dUTP nick-end labelling (TUNEL) -William's E medium (WE)

Keloid disease (KD) is a common fibroproliferative disorder of unknown etiopathogenesis. Its unique occurrence in human skin and lack of animal models pose challenges for KD research. The lack of a suitable model in KD and overreliance on cell culture has hampered the progress in developing new treatments. Therefore, we evaluated the effect of two promising candidate antifibrotic therapies: ( À )-epigallocatechin-3-gallate (EGCG) and plasminogen activator inhibitor-1 (PAI-1) silencing in a long-term human keloid organ culture (OC). Four millimeters of air-liquid interface (ALI) keloid explants on collagen gel matrix in serum-free medium (n ¼ 8 cases) were treated with different modalities (EGCG treatment; PAI-1 knockdown by short interfering RNA (siRNA) and application of dexamethasone (DEX) as control). Normal skin (n ¼ 6) was used as control (only for D0 keloid-untreated comparison). Besides routine histology and quantitative (immuno-) histomorphometry, the key phenotypic and growth parameters of KD were assessed. Results demonstrated that EGCG reduced keloid volume significantly (40% by week 4), increased apoptosis (Z40% from weeks 1 to 4), and decreased proliferation (r17% in week 2). EGCG induced epidermal shrinkage, reduced collagen-I and -III at mRNA and protein levels, depleted 98% of keloid-associated mast cells, and reduced the percentage of both cellularity and blood vessel count by week 4. Knockdown of PAI-1 significantly reduced keloid volume by 28% in week 4, respectively, and reduced collagen-I and -III at both mRNA and protein levels. As expected, DEX increased keloid apoptosis, decreased keloid proliferation, and collagen synthesis, but induced connective tissue growth factor overexpression. In conclusion, using keloid OC model, we provide the first functional evidence for testing candidate antifibrotic compounds in KD. We show that EGCG and PAI-1 silencing effectively inhibits growth and induces shrinkage of human keloid tissue in situ. Therefore, the application of EGCG, PAI-1 silencing, and other emerging compounds tested using this model may provide effective treatment and potentially aid in the prevention of recurrence of KD following surgery. Keloid disease (KD) is a benign hyperproliferative dermal disease of unknown etiopathogenesis with ill-defined treatment, 1 which is unique to humans. 2 KD can arise following an abnormal wound healing process in genetically susceptible individuals. 2 The hallmark of KD is excessive deposition of extracellular matrix (ECM) in the dermis. 3 The lack of an animal model that can truly mimic human KD in vivo condition imposes limitations when investigating functional activities of potential therapeutic agents in treating KD. 4,5 However, these models have failed to provide the essential components of skin tissue that occur in vivo, such as mature ECM, blood vessels, inflammatory cells, and intrinsic and extrinsic biochemical interactions. Therefore, the ultimate aim of this study was to determine the applicability of recent research findings in existing i...

Vitamin D is proposed to have a potential role in the pathogenicity, clinical presentation, prognosis, complications, and treatment of several diseases. In addition to its well-known role in calcium metabolism, vitamin D regulates both innate and adaptive immunity, and subsequently modulates the antiviral and antibacterial inflammatory immune responses. In view of the emerging coronavirus disease 2019 (COVID-19) pandemic, searching for potential therapeutic and protective strategies is of urgent interest, and vitamin D is one of the promising agents in this field. In this review, we present data from literature that supports the promising role of vitamin D in treatment and/or prevention of several infections including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review summarizes vitamin D metabolism and its role in inflammation, thrombosis and immune regulation. It also reviews, in short, the role of vitamin D and the impact of its deficiency in several infections namely tuberculosis, influenza, human immunodeficiency virus (HIV), and SARS-CoV-2. Considering the roles of vitamin D on immune modulation, controlling of thrombosis, and attacking several microorganisms, the current review will elaborate on the association between these salient roles of vitamin D and the pathogenicity of various infectious agents including COVID-19. Consequently, the comprehensive finding of the current review shows a possible significant impact of vitamin D supplement as a hope in preventing, treating, and/or improving the progression of certain infections, specifically during the worldwide attempts to fight against the COVID-19 pandemic and minimize the severity of health complications encountered accordingly. In addition, avoiding a status of vitamin D deficiency to obtain its positive effects on the immune system and its protective mechanism during infections will be a general benefit overall.