Purpose

Recent animal studies have discovered dysregulation of local inflammatory activity as a novel mechanism to explain fat and connective tissue accumulation in the multifidus muscle in association with intervertebral disc (IVD) degeneration/injury. This study aimed to test whether similar mechanisms are active in humans by investigation of whether expression of inflammatory genes in the multifidus muscle differed between individuals with low and high levels of intra-muscular fat in the muscle. The secondary aims were to compare inflammatory gene expression in the intra-muscular, subcutaneous and epidural fat between groups.

Methods

Muscle and fat were procured from 24 individuals undergoing spine surgery for IVD herniation. Gene expression was quantified using qPCR assays. Participants were allocated to high- and low-fat infiltration groups based on clinical assessment of multifidus fat using Kjaer grading of MRI.

Results

TNF expression in the multifidus muscle was greater in participants with high rather than low levels of fat infiltration. This group also had greater expression of leptin, but lower arginase-1 (marker of anti-inflammatory M2 macrophages) in intra-muscular and subcutaneous adipose tissue, and greater expression of TNF, adiponectin and nitric oxide synthase 2 (marker of pro-inflammatory M1 macrophages) in epidural fat.

Conclusion

The results support the hypothesis that IVD degeneration is associated with dysregulation of the inflammatory state of the local multifidus muscle, which provides initial evidence for translation of some, but not all, observations from recent animal studies to humans. Discovery of inflammatory dysregulation in epidural adipose tissue has potential for broad impact on tissue health and LBP symptoms.

中文翻译：

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在进行椎间盘突出症手术的个体中，多发肌中的脂肪浸润与肌肉和硬膜外脂肪组织中炎性细胞因子的表达有关。

目的

最近的动物研究发现，局部炎症活动失调是一种新机制，可解释多发性肌肉中脂肪和结缔组织积累与椎间盘退变/损伤相关。这项研究旨在通过调查肌肉中肌肉脂肪含量低和高的个体之间，多裂肌中炎症基因的表达是否不同，来测试相似的机制是否在人类中起作用。次要目的是比较两组之间肌肉内，皮下和硬膜外脂肪中炎症基因的表达。

方法

肌肉和脂肪是从接受过脊柱手术的24位患者中进行IVD疝气获取的。使用qPCR测定法定量基因表达。使用MRI的Kjaer分级，根据多发脂肪的临床评估，将参与者分为高脂和低脂浸润组。

结果

脂肪浸润水平高而不是低的参与者在多裂肌中的TNF表达更高。该组在肌肉和皮下脂肪组织中瘦素的表达也较高，而精氨酸酶-1（抗炎M2巨噬细胞的标志物）较低，而TNF，脂联素和一氧化氮合酶2（促炎性标志物）的表达也较高。 M1巨噬细胞）在硬膜外脂肪中。

结论

结果支持以下假设：IVD变性与局部多指肌的炎症状态失调有关，这为从最近动物研究向人类提供的一些（但不是全部）观察结果提供了初步证据。在硬膜外脂肪组织中发现炎症失调可能会对组织健康和LBP症状产生广泛影响。