Department of Pharmaceutical Sciences, MSC09 5360, 1 University of New Mexico, Albuquerque, NM, 87131-0001, USA.
Department of Anatomy and Neurobiology, Virginia Commonwealth University, PO Box 980709, Richmond, VA, 23298, USA.
Part Fibre Toxicol. 2021 Sep 8;18(1):34. doi: 10.1186/s12989-021-00427-w.
Multiwalled carbon nanotubes (MWCNT) are an increasingly utilized engineered nanomaterial that pose the potential for significant risk of exposure-related health outcomes. The mechanism(s) underlying MWCNT-induced toxicity to extrapulmonary sites are still being defined. MWCNT-induced serum-borne bioactivity appears to dysregulate systemic endothelial cell function. The serum compositional changes after MWCNT exposure have been identified as a surge of fragmented endogenous peptides, likely derived from matrix metalloproteinase (MMP) activity. In the present study, we utilize a broad-spectrum MMP inhibitor, Marimastat, along with a previously described oropharyngeal aspiration model of MWCNT administration to investigate the role of MMPs in MWCNT-derived serum peptide generation and endothelial bioactivity.
C57BL/6 mice were treated with Marimastat or vehicle by oropharyngeal aspiration 1 h prior to MWCNT treatment. Pulmonary neutrophil infiltration and total bronchoalveolar lavage fluid protein increased independent of MMP blockade. The lung cytokine profile similarly increased following MWCNT exposure for major inflammatory markers (IL-1β, IL-6, and TNF-α), with minimal impact from MMP inhibition. However, serum peptidomic analysis revealed differential peptide compositional profiles, with MMP blockade abrogating MWCNT-derived serum peptide fragments. The serum, in turn, exhibited differential potency in terms of inflammatory bioactivity when incubated with primary murine cerebrovascular endothelial cells. Serum from MWCNT-treated mice led to inflammatory responses in endothelial cells that were significantly blunted with serum from Marimastat-treated mice.
Thus, MWCNT exposure induced pulmonary inflammation that was largely independent of MMP activity but generated circulating bioactive peptides through predominantly MMP-dependent pathways. This MWCNT-induced lung-derived bioactivity caused pathological consequences of endothelial inflammation and barrier disruption.
多壁碳纳米管（MWCNT）是一种越来越被广泛应用的工程纳米材料，其具有与暴露相关的健康后果的重大潜在风险。MWCNT 诱导的肺外部位毒性的机制仍在确定中。MWCNT 诱导的血清源性生物活性似乎会使全身内皮细胞功能失调。MWCNT 暴露后的血清成分变化已被确定为碎片化内源性肽的激增，这些肽可能源自基质金属蛋白酶（MMP）活性。在本研究中，我们使用广谱 MMP 抑制剂 Marimastat 以及先前描述的经口咽吸入 MWCNT 给药模型，研究 MMP 在 MWCNT 衍生的血清肽产生和内皮生物活性中的作用。
C57BL/6 小鼠通过经口咽吸入在接受 MWCNT 治疗前 1 小时接受 Marimastat 或载体治疗。肺部中性粒细胞浸润和总支气管肺泡灌洗液蛋白增加与 MMP 阻断无关。肺细胞因子谱也随着 MWCNT 暴露而增加，主要炎症标志物（IL-1β、IL-6 和 TNF-α）增加，而 MMP 抑制的影响很小。然而，血清肽组学分析显示出不同的肽组成谱，MMP 阻断消除了 MWCNT 衍生的血清肽片段。反过来，当与原代小鼠脑血管内皮细胞孵育时，血清表现出不同的炎症生物活性。用 Marimastat 处理过的小鼠的血清会导致内皮细胞发生炎症反应，而用 MWCNT 处理过的小鼠的血清则会显著减弱这种反应。
因此，MWCNT 暴露引起的肺部炎症在很大程度上独立于 MMP 活性，但通过主要依赖 MMP 的途径产生循环生物活性肽。这种 MWCNT 诱导的肺源性生物活性导致内皮炎症和屏障破坏的病理后果。
