Inside-out and outside-in organotypic normal human skin culture: JAK-STAT pathway is activated after pro-inflammatory psoriatic cytokine exposure.

The Janus kinases-signal transducers and activators of transcription (JAK-STAT) signalling pathway are a pleiotropic cascade that involves ligands such as cytokines, hormones, and growth factors. Among cytokines, interleukin (IL)-17, IL-22, IL-23, and tumour necrosis factor (TNF)-alpha play a pivotal role in psoriasis. We aimed at investigating in an organotypic experimental model of normal human skin (n = 7 women between 20-40 years old, non-smokers) the early, direct, and specific effects of IL-17, IL-22, IL-23, TNF-alpha and a combination of the four cytokines (Mix) on the JAK-STAT/pathway. The expression of the psoriatic marker keratin (K) 17 was analyzed by immunofluorescence and molecular techniques after exposure to IL-23 or Mix. The Mix elicited a strong K17 up-regulation in keratinocytes at 72 h, reinforcing the hypothesis of a synergistic effect of different cytokines. High levels of JAK1 and STAT3 activation were detected, suggesting the involvement of JAK1/STAT3 pathway in the upregulation of K17. As the present study in an organotypic model of human skin reports a variable expression of JAK-STAT upon different cytokine stimuli and most of the JAK inhibitors for the psoriasis treatment have proven to have a clinical efficacy, these observations have a relevance to better understand the mechanisms of JAK-inhibitors in the skin.

Influence on chondrogenesis of human osteoarthritic chondrocytes in co-culture with donor-matched mesenchymal stem cells from infrapatellar fat pad and subcutaneous adipose tissue.

Co-culture of mesenchymal stem cells (MSCs) and articular chondrocytes (ACs) has been proposed for autologous cartilage cell-based therapies, to overcome the issues associated to limited availability of articular chondrocytes (ACs). To evaluate the potentiality of a co-culture approach in aged osteoarthritic patients, MSCs from infrapatellar fat pad (IFP-MSCs) and knee subcutaneous adipose tissue (ASCs) were co-cultured with donor-matched osteoarthritic, expanded and cryopreserved, ACs in a 75%/25% ratio. Co-cultures were prepared also from nasal chondrocytes (NCs) to evaluate their possible use as an alternative to ACs. Pellets were differentiated for 14 days, using mono-cultures of each cell type as reference. Chondrogenic genes SOX9, COL2A1, ACAN were less expressed in co-cultures compared to ACs and NCs. Total GAGs content in co-cultures did not differ significantly from values predicted as the sum of each cell type contribution corrected for the co-culture ratio, as confirmed by histology. No significant differences were observed for GAGs/DNA in mono-cultures, demonstrating a reduced chondrogenic potential of ACs and NCs. In conclusion, a small percentage of expanded and cryopreserved ACs and NCs did not lead to IFP-MSCs and ASCs chondro-induction. Our results suggest that chondrogenic potential and origin of chondrocytes may play a relevant role in the outcome of co-cultures, indicating a need for further investigations to demonstrate their clinical relevance in the treatment of aged osteoarthritic patients.