The role of inflammation in chronic tendon/ligament injury is hotly debated. There is less debate about inflammation following acute injury. To better understand the effect of acute inflammation, in this study we developed a multi-cytokine model of inflammatory tendinitis. The combined treatment with TNF-α, IL-1β, and IL-6, at dosages well below what are routinely used in vitro, decreased the mechanical properties and collagen content of engineered human ligaments. Treatment with this cytokine mixture resulted in an increase in phospho-NF-κB and MMP-1, did not affect procollagen production, and decreased STAT3 phosphorylation relative to controls. Using this more physiologically relevant model of acute inflammation, we inhibited NF-κB or JAK1 signaling in an attempt to reverse the negative effects of the cytokine mixture. Surprisingly, NF-κB inhibition led to an even greater decrease in mechanical function and collagen content. By contrast, inhibiting JAK1 led to an increase in mechanical properties, collagen content and thermal stability concomitant with a decrease in MMP-1. Our results suggest that inhibition of JAK1, not NF-κB, reverses the negative effects of pro-inflammatory cytokines on collagen content and mechanics in engineered human ligaments.

炎症在慢性肌腱/韧带损伤中的作用引起了激烈的争论。关于急性损伤后炎症的争论较少。为了更好地了解急性炎症的影响，在这项研究中，我们开发了炎症性肌腱炎的多细胞因子模型。TNF-α、IL-1β 和 IL-6 的联合治疗，其剂量远低于体外常规使用的剂量，降低了工程人类韧带的机械性能和胶原蛋白含量。与对照组相比，用这种细胞因子混合物治疗导致磷酸-NF-κB 和 MMP-1 增加，不影响前胶原产生，并降低 STAT3 磷酸化。利用这种生理上更相关的急性炎症模型，我们抑制了 NF-κB 或 JAK1 信号传导，试图扭转细胞因子混合物的负面影响。令人惊讶的是，NF-κB 抑制导致机械功能和胶原蛋白含量的更大下降。相比之下，抑制 JAK1 会导致机械性能、胶原蛋白含量和热稳定性增加，同时 MMP-1 减少。我们的结果表明，抑制 JAK1（而非 NF-κB）可以逆转促炎细胞因子对工程人类韧带中胶原蛋白含量和力学的负面影响。