Effect of chemotherapy on pulmonary epithelial permeability in lung cancer

Clinical significance of microbial colonization identified by initial bronchoscopy in patients with lung cancer requiring chemotherapy

Background

There are limited data on the association between bronchial colonization and respiratory infections in people with lung cancer requiring cytotoxic chemotherapy. We investigated whether bronchial colonization in initial bronchoscopy specimens can predict the development of pneumonia after chemotherapy in patients with lung cancer.

Methods

Four hundred thirteen patients with lung cancer included in the Catholic Medical Center lung cancer registry were enrolled from March 2015 to August 2018. Demographic data, microbiology results, development of pneumonia after chemotherapy, and clinical information about lung cancer were analyzed retrospectively.

Results

A total of 206 lung cancer patients treated with chemotherapy were included in the analysis. Forty patients (19.4%) had positive results for the bronchial washing culture during the initial evaluation of lung cancer. The most common organisms were Klebsiella pneumoniae (n=14) and Streptococcus pneumoniae (n=6) in the surveillance culture, and Pneumocystis jirovecii (n=12) and Staphylococcus aureus (n=8) at the time of pneumonia development. Eighty-nine patients (43.2%) had pneumonia after chemotherapy, but the occurrence of pneumonia did not differ according to the colonization. There were no patients for whom the initial isolated organism was a causative microbe for the development of pneumonia after or during chemotherapy. The pneumonia group had poorer prognosis than the non-pneumonia group (378 vs. 705 days, P=0.0004).

Conclusions

Microbial colonization in bronchoscopy specimens was not associated with pneumonia development or mortality after chemotherapy for lung cancer. This finding suggests that testing surveillance culture may not be helpful for predicting pneumonia or improving survival in lung cancer patients with chemotherapy.

Menadione causes endothelial barrier failure by a direct effect on intracellular thiols, independent of reactive oxidant production

Menadione (MQ), a quinone used with cancer chemotherapeutic agents, causes cytotoxicity to endothelial cells (EC). Previous studies have suggested that MQ induces an oxidative stress and dysfunction in EC by either increasing hydrogen peroxide (H(2)O(2)) production or depleting intracellular glutathione (GSH), the main intracellular antioxidant. Since a primary function of EC is to form a barrier to fluid movement into tissues, protecting organs from edema formation and dysfunction, our aim was to see if MQ would cause a barrier dysfunction and to ascertain the mechanism. Using diffusional permeability to fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) as a measure of barrier function, we found that 15 micro M MQ incubated with a bovine pulmonary artery EC (BPAEC) monolayer for 4 h produced a profound barrier failure ( approximately 7-fold increase in permeability) with a parallel fall in glutathione, almost to depletion. These two events were highly correlated. Immunofluorescent imaging showed formation of paracellular holes consistent with a loss or rearrangement of cell-cell and cell-matrix adhesion molecules. H(2)O(2) (100 micro M), a concentration which gave about the same increase in permeability as MQ, only slightly decreased GSH concentration. Antioxidants, such as catalase (CAT) and dimethylthiourea (DMTU), which were able to block the H(2)O(2)-induced changes, had no effect on the MQ-induced permeability and GSH changes, suggesting that H(2)O(2) was not involved in MQ-induced effects. MQ caused a severe EC cytotoxicity as judged by lactate dehydrogenase (LDH) leakage from the EC, whereas H(2)O(2) caused only a minor increase. Also, MQ profoundly inhibited the activities of glucose-6-phosphate dehydrogenase (G6PDH) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), key thiol enzymes involved in glutathione and ATP metabolism, whereas H(2)O(2) produced only a slight decrease in these activities. We conclude that the cytotoxicity of MQ and resulting barrier dysfunction correlate with GSH depletion and inactivation of key metabolic enzymes, compromising antioxidant defenses, rather than being consistent with H(2)O(2)-mediated oxidative stress.