Background: Canine intervertebral disc disease (IVDD) represents a significant clinical problem in veterinary medicine, with similarities to the human pathology. Host-derived damage-associated molecular patterns like fibronectin fragments (FnF) that develop during tissue dysfunction may be of specific relevance to IVD pathologies by inducing an inflammatory response in resident cells.

Aim: This project aimed to determine the presence and pathobiological role of FnF during IVD herniation in dogs, with a focus on inflammation.

Methods: Herniated nucleus pulposus (NP) material from five dogs as well as non-herniated adjacent NP material from three dogs was collected during spinal surgery required due to acute IVD herniation. The presence of different types of FnF were determined by Western blot analysis. NP cells isolated from six herniated canine IVDs were then exposed to 30 kDa FnF. NP cell inflammation and catabolism was examined by investigating the expression of IL-1β, IL-6, IL-8, and COX-2, as well as MMP-1 and MMP-3 by qPCR (all targets) and ELISA (IL-6, PGE₂).

Results: Amongst multiple sized FnF (30, 35, 45, and >170kDa), N-terminal fragments at a size of ~30 kDa were most consistently expressed in all five herniated IVDs. Importantly, these fragments were exclusively present in herniated, but not in non-herniated IVDs. Exposure of canine NP cells to 500 nM 30 kDa FnF caused a significant upregulation of IL-6 (62.5 ± 79.9, p = 0.032) and IL-8 (53.0 ± 75.7, p = 0.031) on the gene level, whereas IL-6 protein analysis was inconclusive. Donor-donor variation was observed in response to FnF treatment, whereby this phenomenon was most evident for COX-2, with three donors demonstrating a significant downregulation (0.67 ± 0.03, p = 0.003) and three donors showing upregulation (6.9 ± 5.5, p = 0.21). Co-treatment with Sparstolonin B, a TRL-2/TRL-4 antagonist, showed no statistical difference to FnF treatment alone in all tested target genes.

Conclusion: Given the presence of the 30 kDa FnF in canine herniated IVDs and the proinflammatory effect of 30 kDa FnF on NP cells, we concluded that the accumulation of FnF may be involved in the pathogenesis of canine IVDD. These results correspond to the findings in humans with IVDD.

背景：犬椎间盘疾病（IVDD）代表了兽医学中的重大临床问题，与人类病理学相似。通过在宿主细胞中诱导炎症反应，在组织功能障碍期间形成的宿主衍生的损伤相关分子模式，如纤连蛋白片段（FnF），可能与IVD病理学特别相关。

目标： 该项目旨在确定犬IVD疝期间FnF的存在和病理生物学作用，重点是炎症。

方法：在由于急性IVD疝而需要的脊柱外科手术期间，收集了五只狗的椎间盘突出髓核（NP）材料和三只狗的非椎间盘突出相邻NP材料。通过蛋白质印迹分析确定不同类型的FnF的存在。然后，将从六个犬齿犬IVD中分离出的NP细胞暴露于30 kDa FnF。通过qPCR（所有靶标）和ELISA（IL-β）检测IL-1β，IL-6，IL-8和COX-2以及MMP-1和MMP-3的表达来检查NP细胞的炎症和分解代谢6，PGE ₂）。

结果：在多个大小的FnF（30、35、45和> 170kDa）中，大小约为30 kDa的N末端片段在所有五个突出的IVD中最一致地表达。重要的是，这些片段仅存在于突出的IVD中，而不存在于突出的IVD中。犬NP细胞暴露于500 nM 30 kDa FnF导致IL-6显着上调（62.5±79.9，p = 0.032）和IL-8（53.0±75.7， p= 0.031）在基因水平上，而IL-6蛋白分析尚无定论。在FnF处理中观察到了供体-供体的变化，这种现象在COX-2中最为明显，其中三个供体表现出明显的下调（0.67±0.03，p = 0.003），三个供体显示出上调（6.9±5.5， p= 0.21）。在所有测试的靶基因中，与TRL-2 / TRL-4拮抗剂Sparstolonin B共同治疗与单独的FnF治疗无统计学差异。

结论：考虑到犬突出的IVDs中存在30 kDa FnF以及30 kDa FnF对NP细胞的促炎作用，我们得出结论，FnF的积累可能与犬IVDD的发病机理有关。这些结果与IVDD患者的发现相对应。