New insights into tenocyte-immune cell interplay in an in vitro model of inflammation

Abstract

Inflammation plays an important role in the development and resolution of tendon diseases, but underlying mechanisms are poorly understood. We therefore aimed to analyze the response of human tenocytes to inflammatory stimuli and to uncover their interplay with macrophages in vitro. Tenocytes from human ruptured supraspinatus tendons (n = 10) were treated for three days with a stimulation mixture derived from activated mononuclear cells isolated from healthy human peripheral blood. Significantly increased expression levels of selected adhesion- and human leukocyte antigen (HLA)-molecules, and enhanced interleukin (IL)-6 release were detected by flow cytometry. Tenocyte stimulation with the pro-inflammatory cytokines interferon gamma, tumor necrosis factor alpha and IL-1ß triggered similar changes in surface markers and enhanced the release of IL-6, IL-8 and monocyte chemoattractant protein 1 (MCP-1). In co-cultures of macrophages with pre-stimulated tenocytes, macrophages significantly increased CD80 expression, but simultaneously decreased HLA-DR-expression, which are both typical pro-inflammatory polarization markers. Co-cultures also released more IL-6, IL-8, MCP-1 than tenocyte-cultures alone. We demonstrate that tenocytes respond to inflammatory environments in vitro with altered surface marker and cytokine profiles and influence macrophage polarization. Importantly, all changes detected in direct co-cultures were also present in a transwell setting, implicating that communication between the cells involves soluble factors.

Intratendon delivery of leukocyte‐rich platelet‐rich plasma at early stage promotes tendon repair in a rabbit Achilles tendinopathy model

“…Macrophage plays essential roles in promoting inflammation at early stage and resolving inflammation at late stage of tendon healing (Motwani & Gilroy, ). In the tendon injury setting, M1 cells predominate early and are pro‐inflammatory via release of IL‐1β, TNF‐α, and IL‐6, whereas M2 macrophages accumulate later and are anti‐inflammatory via release of IL‐10 and TGF‐β1 (Stolk et al, ). Ablation study in tendon demonstrated that M1 promoted inflammation and repair process during early stage, whereas M2 suppress inflammation and resolving scarring at later stage (Millar et al, ).…”

“…Macrophage plays essential roles in promoting inflammation at early stage and resolving inflammation at late stage of tendon healing (Motwani & Gilroy, 2015). In the tendon injury setting, M1 cells predominate early and are pro-inflammatory via release of IL-1β, TNF-α, and IL-6, whereas M2 macrophages accumulate later and are antiinflammatory via release of IL-10 and TGF-β1 (Stolk et al, 2017).…”

In Vivo and In Vitro Mechanical Loading of Mouse Achilles Tendons and Tenocytes—A Pilot Study

“…Our in vitro data demonstrated the absence of endogenous expression of IL-1β and TNF-α in both groups. Studies show that tenocytes are able to express pro-inflammatory cytokines by themselves in response to cytokines or in co-culture with macrophages [63,64]. In vitro mechanical loading that induces an inflammatory response comparable to over-load can be used to investigate tenocyte behavior and their mechanism to cope with inflammation.…”

Extracellular vesicles from regenerative human cardiac cells act as potent immune modulators by priming monocytes

“…The expression of surface markers on cells was investigated by staining with multicolour panels of humanspecific fluorescence labelled antibodies according to the method previously described [76] and measured by flow cytometry. Three different antibody panels were used to stain immune cells.…”

“…Peripheral blood mononuclear cells (PBMCs) were isolated from healthy blood donors by using a Biocoll gradient as described previously [76]. T cells (CD3 + cells) and monocytes (CD14 + cells) were enriched from the PBMCs by magnetic activated cell sorting (MACS).…”