Urabe Hiroshi, Terashima Tomoya, Lin Fan, Kojima Hideto, Chan Lawrence
Department of Medicine, Baylor College of Medicine, One Baylor Plaza (MS: BCM185), Houston, TX, 77030, USA.
Diabetologia. 2015 Feb;58(2):402-10. doi: 10.1007/s00125-014-3440-4. Epub 2014 Nov 16.
AIMS/HYPOTHESIS: Dysregulation of biochemical pathways in response to hyperglycaemia in cells intrinsic to the nervous system (Schwann cells, neurons, vasa nervorum) are thought to underlie diabetic peripheral neuropathy (DPN). TNF-α is a known aetiological factor; Tnf-knockout mice are protected against DPN. We hypothesised that TNF-α produced by a small but specific bone marrow (BM) subpopulation marked by proinsulin production (proinsulin-producing BM-derived cells, PI-BMDCs) is essential for DPN development.
We produced mice deficient in TNF-α, globally in BM and selectively in PI-BMDCs only, by gene targeting and BM transplantation, and induced diabetes by streptozotocin. Motor and sensory nerve conduction velocities were used to gauge nerve dysfunction. Immunocytochemistry, fluorescence in situ hybridisation (FISH) and PCR analysis of dorsal root ganglia (DRG) were employed to monitor outcome.
We found that loss of TNF-α in BM only protected mice from DPN. We developed a strategy to delete TNF-α specifically in PI-BMDCs, and found that PI-BMDC-specific loss of TNF-α protected against DPN as robustly as loss of total BM TNF-α. Selective loss of PI-BMDC-derived TNF-α downregulated TUNEL-positive DRG neurons. FISH revealed PI-BMDC-neuron fusion cells in the DRG in mice with DPN; fusion cells were undetectable in non-diabetic mice or diabetic mice that had lost TNF-α expression selectively in the PI-BMDC subpopulation.
CONCLUSIONS/INTERPRETATION: BMDC-specific TNF-α is essential for DPN development; its selective removal from a small PI-BMDC subpopulation protects against DPN. The pathogenicity of PI-BMDC-derived TNF-α may have important therapeutic implications.
目的/假设：神经系统固有细胞（雪旺细胞、神经元、神经滋养血管）对高血糖的生化途径失调被认为是糖尿病周围神经病变（DPN）的基础。肿瘤坏死因子-α（TNF-α）是已知的病因因素；TNF基因敲除小鼠可预防DPN。我们假设由一小部分特定的骨髓（BM）亚群产生的TNF-α（以产生胰岛素原标记，即产生胰岛素原的骨髓来源细胞，PI-BMDCs）对DPN的发展至关重要。
我们通过基因靶向和骨髓移植，制备了全身骨髓中缺乏TNF-α以及仅在PI-BMDCs中选择性缺乏TNF-α的小鼠，并通过链脲佐菌素诱导糖尿病。运动和感觉神经传导速度用于评估神经功能障碍。采用免疫细胞化学、荧光原位杂交（FISH）和背根神经节（DRG）的PCR分析来监测结果。
我们发现仅骨髓中TNF-α的缺失可保护小鼠免受DPN。我们开发了一种在PI-BMDCs中特异性删除TNF-α的策略，发现PI-BMDCs中TNF-α的特异性缺失与全身骨髓TNF-α缺失一样能有效预防DPN。PI-BMDCs来源的TNF-α的选择性缺失下调了TUNEL阳性的DRG神经元。FISH显示DPN小鼠的DRG中有PI-BMDC-神经元融合细胞；在非糖尿病小鼠或在PI-BMDC亚群中选择性缺失TNF-α表达的糖尿病小鼠中未检测到融合细胞。
结论/解读：BMDCs特异性TNF-α对DPN的发展至关重要；从一小部分PI-BMDC亚群中选择性去除它可预防DPN。PI-BMDCs来源的TNF-α的致病性可能具有重要的治疗意义。
