Although fine particulate matter (FPM) in air pollutants and tobacco smoke is recognized as a strong carcinogen and global threat to public health, its biological mechanism for inducing lung cancer remains unclear. Here, by investigating FPM's bioactivities in lung carcinoma mice models, we discover that these particles promote lung tumor progression by inducing aberrant thickening of tissue matrix and hampering migration of anti-tumor immunocytes. Upon inhalation into lung tissue, these FPM particles abundantly adsorb peroxidasin (PXDN) - an enzyme mediating type IV collagen (Col IV) crosslinking - onto their surface. The adsorbed PXDN exerts abnormally high activity to crosslink Col IV via increasing the formation of sulfilimine bonds at the NC1 domain, leading to an overly dense matrix in the lung tissue. This disordered structure decreases the mobility of cytotoxic CD8+ T lymphocytes into the lung and consequently impairs the local immune surveillance, enabling the flourishing of nascent tumor cells. Meanwhile, inhibiting the activity of PXDN abolishes the tumor-promoting effect of FPM, indicating the key impact of aberrant PXDN activity on the tumorigenic process. In summary, our finding elucidates a new mechanism for FPM-induced lung tumorigenesis and identifies PXDN as a potential target for treatment or prevention of the FPM-relevant biological risks.

Functional engineered nanoparticles are promising drug delivery carriers. As the construction of a functional nanocarrier always needs the optimization of multiple technical variables, efficient in vitro high-throughput evaluation methods would help to shorten the development cycle. In the present study, we generated a tissue mimic of the colon of inflammatory bowel disease (IBD) patients. Generally, Caco-2 cells and THP-1 cells were grown in a 3-D matrix with different number, spatial distribution and specific extracellular cell matrix (ECM) composition according to real healthy and inflamed animal colon tissues. After interlerukin-1β/lipopolysaccharide (LPS) stimulation, the artificial model closely resembled the pathological features of IBD patient's colon, including massive cytokines and mucus production, epithelium defect and leukocytic infiltration. The tissue and cellular uptake of three different nanoparticles in the artificial model was similar to that in 2,4,6-trinitrobenzenesulfonic acid (TNBS) colitic mice. Most importantly, our artificial tissue can be placed into 96-well plates for high-throughput screening of drug delivery carriers for the treatment of IBD. Our study suggested a readily achievable way to improve current methodologies for the development of colon targeted drug delivery systems.