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.

Objectives. 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 conducted by histological and immunohistochemical techniques. Assessment of certain oxidative stress markers were also conducted.

Results. Group II showed significant 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.