Diesel vehicles-derived PM2.5 induces lung and cardiovascular injury attenuates by Securiniga suffruticosa: Involvement of NF-κB-mediated NLRP3 inflammasome activation pathway

Respiratory exposure to Particulate matter (PM), including Diesel exhaust particulate (DEP), causes oxidative stress-induced lung inflammation. Especially, fine particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) is a serious air pollutant associated with various health problems including cardiovascular diseases. The present study aimed to examine the inhibitory effect of Securiniga suffruticosa (S. suffruiticosa) on DEP and PM-induced lung and cardiovascular diseases. Mice inhaled DEP by using nebulizer chamber for two weeks. Treatment with S. suffruiticosa reduced the expression of C-X-C motif ligand 1/2 in bronchoalveolar lavage fluid and Muc5ac, ICAM-1, TNF-⍺, IL-6 mRNA in lung were also attenuated by S. suffruiticosa. In thoracic aorta, DEP increased CAMs, TNF-⍺ and inflammasome markers such as NLRP3, Caspase-1, and ASC. However, S. suffruiticosa suppressed these levels. S. suffruiticosa inhibited PM2.5 induced production of intracellular reactive oxygen species (ROS); and inhibited the translocation of NF-κB p65 to the nucleus in human umbilical vein endothelial cells. Taken together, this study proved that exposure to PM2.5 induced both lung and vascular inflammation, however, S. suffruiticosa attenuated this injury via the downregulation of the NLRP3 signaling pathway. These findings suggest that S. suffruiticosa may have potential therapeutic benefit against air pollution-mediated lung and cardiovascular diseases.

Experimental respiratory exposure to putative Gulf War toxins promotes persistent alveolar macrophage recruitment and pulmonary inflammation

AIMS

Respiratory disorders are a prominent component of Gulf War Illness. Although much of the underlying mechanisms of Gulf War Illness remain undefined, chronic immune dysfunction is a consistent feature of this multi-symptomatic, multi-organ disorder. Alveolar macrophages represent the predominant mononuclear phagocytes of the pulmonary mucosa, orchestrating the host response to pathogens and environmental stimuli. Herein, we sought to characterize the innate immune response of the pulmonary mucosa, with a focus on macrophages, to experimental respiratory exposure to two putative Gulf War Toxins (GWTs).

MATERIALS AND METHODS

Utilizing commercially available instrumentation, we evaluated the effect of aerosolized exposure to the pesticide malathion and diesel exhaust particulate (DEP) on the immune composition and inflammatory response of the lung in FVB/N mice using multiparametric spectral cytometry, cytokine analysis, and histology.

KEY FINDINGS

Aerosolized GWTs induced gross pulmonary pathology with transient recruitment of neutrophils and sustained accumulation of alveolar macrophages to the lung for up to two weeks after exposure cessation. High-dimensional cytometry and unbiased computational analysis identified novel myeloid subsets recruited to the lung post-exposure driven by an influx of peripheral monocyte-derived progenitors. DEP and malathion, either alone or in combination, induced soluble mediators in bronchoalveolar lavage indicative of oxidative stress (PGF2α), inflammation (LTB4, TNFα, IL-12), and immunosuppression (IL-10), that were sustained or increased two weeks after exposures concluded.

SIGNIFICANCE

These findings indicate that macrophage accumulation and pulmonary inflammation induced by GWTs continue in the absence of toxin exposure and may contribute to the immunopathology of respiratory Gulf War Illness.

Effects of diesel exhaust particles on the condition of mouse ocular surface

In order to evaluate the effects of diesel exhaust particles (DEP) on the ocular surface, different concentrations (100 and 1000 μg/ml) of DEP eye drops were administered on the mouse ocular surface for a period of 28 days. After DEP treatment, the corneal epithelial permeability to Oregon Green Dextran was studied, which increased proportionally with time. Also, the number of corneal epithelial cell layers significantly increased, which was accompanied with a high Ki67 expression. On the other hand, the number of goblet cells in the conjunctival fornix were reduced, and apoptotic cells were detected in the corneal and conjunctival epithelium by TUNEL assay in the DEP treated group, along with increased Caspase 3/8 expression. Furthermore, the number of CD4 positive cells significantly increased in the conjunctiva, while NF-κB p65 (phospho S536) expression was elevated in the cornea and also the conjunctiva. Our data revealed that the topical administration of DEP on the ocular surface in mouse disrupted the organized structure of the ocular surface and induced an inflammation of the cornea and conjunctiva.