The anthropogenic particulate matter (PM), suspended air dust that can be inhaled by humans and deposited in the lungs, is one of the main pollutants in the industrialized cities atmosphere. Recent studies have shown that PM has adverse effects on respiratory diseases. These effects are mainly due to the ultrafine particles (PM0.1, PM < 100 nm), which, thanks to their PM size, are efficiently deposited in nasal, tracheobronchial, and alveolar regions. Pulmonary macrophages are a heterogeneous cell population distributed in different lung compartments, whose role in inflammatory response to injury is of particular relevance. In this study, we investigated the effect of PM0.1 on Human Lung Macrophages (HLMs) activation evaluated as proinflammatory cytokines and chemokine release, Reactive Oxygen Species (ROS) production and intracellular Ca²⁺concentration ([Ca²⁺]_i). Furthermore, PM0.1, after removal of organic fraction, was fractionated in nanoparticles both smaller (NP20) and bigger (NP100) than 20 nm by a properlydeveloped analytical protocol, allowed isolating their individual contribution. Interestingly, while PM0.1 and NP20 induced stimulatory effects on HLM cytokines release, NP100 had not effect. In particular, PM0.1 induced IL-6, IL-1β, TNF-α, but not CXCL8, release from HLMs. Moreover, PM0.1, NP20 and NP100 did not induce β-glucuronidase release, a preformed mediator contained in HLMs. The long time necessary for cytokines release (18 h) suggested that PM0.1 and NP20 could induce ex-novo production of the tested mediators. Accordingly, after 6 h of incubation, PM0.1 and NP20 induced mRNA expression of IL-6, TNF-α and IL-1β. Moreover, NP20 induced ROS production and [Ca²⁺]_i increase in a time-dependent manner, without producing cytotoxicity.

Collectively, the present data highlight the main proinflammatory role of NP20 among PM fractions. This is particularly of concern because this fraction is not currently covered by legal limits as it is not easily measured at the exhausts by the available technical methodologies, suggesting that it is mandatory to search for new monitoring techniques and strategies for limiting NP20 formation.

人为颗粒物（PM）是可被人类吸入并沉积在肺部的悬浮空气粉尘，是工业化城市大气中的主要污染物之一。最近的研究表明，PM 对呼吸系统疾病有不良影响。这些影响主要是由于超细颗粒（PM0.1，PM < 100 nm），由于它们的 PM 大小，它们有效地沉积在鼻腔、气管支气管和肺泡区域。肺巨噬细胞是分布在不同肺区室的异质细胞群，其在对损伤的炎症反应中的作用特别重要。在这项研究中，我们研究了 PM0.1 对人肺巨噬细胞 (HLM) 活化的影响，评估为促炎细胞因子和趋化因子释放、活性氧 (ROS) 产生和细胞内 Ca²⁺浓度（[Ca ²⁺ ] _i）。此外，PM0.1 在去除有机部分后，通过适当开发的分析方案在小于 20 nm 的纳米颗粒（NP20）和更大（NP100）中分馏，允许分离它们各自的贡献。有趣的是，虽然 PM0.1 和 NP20 诱导了对 HLM 细胞因子释放的刺激作用，但 NP100 没有作用。特别是，PM0.1 诱导 HLM 释放 IL-6、IL-1β、TNF-α，而不是 CXCL8。此外，PM0.1、NP20 和 NP100 不诱导 β-葡萄糖醛酸酶释放，这是 HLM 中包含的一种预先形成的介质。细胞因子释放所需的长时间（18 小时）表明 PM0.1 和 NP20 可以从新诱导测试介质的产生。因此，在孵育 6 小时后，PM0.1 和 NP20 诱导 IL-6、TNF-α 和 IL-1β 的 mRNA 表达。此外，NP20 诱导 ROS 产生和 [Ca ²⁺ ] _i以时间依赖性方式增加，而不产生细胞毒性。

总的来说，目前的数据突出了 NP20 在 PM 组分中的主要促炎作用。这一点尤其值得关注，因为这部分目前不受法律限制，因为它不容易通过可用的技术方法在尾气处测量，这表明必须寻找新的监测技术和策略来限制 NP20 的形成。