Background: Diesel exhaust nanoparticles (DENPs) are one of the most prevalent environmental pollutants that adversely affect human health. DENPs are involved in the occurrence of chronic lung diseases such as COPD, bronchial asthma, chronic bronchitis and cancer. Objective: Evaluation of DENPs damaging effects on the pulmonary tissue and assessment of the possible protective effects of Quercetin (QRT) on the lung tissue via histological, immunohistochemical and biochemical assessment. Materials and Methods: Forty-five albino male rats were divided into 3 groups: Group I (control rats), Group II (DENPs group) received repeated doses of DENPs (180µg/rat) intratracheally every other day for 6 days, Group III (DENPs + QRT) received quercetin orally (60 mg/kg B.Wt.) 1h before DENPs exposure. Examination of Lung tissues were conductedby histological and immunohistochemical techniques. Assessment of certain oxidative stress markers were also conducted. Results: Group II showedsignificant changes in the histological picture of the lung tissue with collapsed alveoli, thick interalveolar septa and marked cellular infiltration. Collagen fibers were markedly increased by DENPs. Quercetin treatment led to amelioration of the histological findings in the lung tissue with marked decrease in collagen fibers. QRT led to significant decrease in iNOS immunoreactivity and increase in PCNA immunoreactivity. Conclusion:Quercetin has protective effects against pulmonary toxicity induced by DENPs via its anti-inflammatory effects and anti-oxidant properties.

Background: Diesel vehicles exhaust contains toxic nanoparticles that drastically affect lung tissue due to their direct cytotoxic effects, induction of oxidative stress, inflammatory signaling pathways and DNA damage. Mesenchymal stem cells (MSCs) exhibit anti-inflammatory effects and efficient regenerative capacity in chronic lung diseases.  Objectives: Evaluation of the effects of MSCs and MSCs-derived micro vesicles (MSCs-MVs) on pulmonary toxicity induced by diesel exhaust nanoparticles (DENPs). Materials and Methods: Sixty male rats were equally divided into: Group I (Control rats), Group II (DENPs group) received repeated doses of DENPs (180μg/rat) intratracheally every other day for 6 days, Group III (MSCs group) received MSCs intravenously (3×106 cells) after the last dose of DENPs and Group IV (MSCs-MVs group) received MSCs-MVs (0.5 mg/mL) intravenously after the last dose of DENPs. Lung tissue were subjected to histological and immunohistochemical assessment. Inflammatory cytokines and bronchoalveolar lavage fluid (BALF) contents of inflammatory cells, albumin, LDH and total proteins were evaluated. Results: Histological picture of lung tissue in DENPs group showed numerous collapsed alveoli, thick interalveolar septa and marked cellular infiltration. Elastic fibers were markedly decreased by DENPs. Increased optical density of NF-κB/p65 immunoreactivity. Bronchoalveolar lavage fluid showed significant elevation of inflammatory cytokines (TNF-a, IL-6), polymorphonuclear leukocytes (PMN), neutrophils, macrophages, LDH, total proteins and albumin. Treatment with either MSCs or MSCs-MVs led to a significant amelioration of all of the aforementioned studied parameters. Conclusion: MSCs-MVs and MSCs showed significant therapeutic effects against DENPs damaging effects on the lung tissues via their regenerative capacity and anti-inflammatory effects.