Aesif, Scott W.

Abstract Lung tissue remodeling in chronic obstructive pulmonary disease (COPD) is characterized by airway wall thickening and/or emphysema. Although the bronchial and alveolar compartments are functionally independent entities, we recently showed comparable alterations in matrix composition comprised of decreased elastin content and increased collagen and hyaluronan contents of alveolar and small airway walls. Out of several animal models tested, surfactant protein C (SPC)-TNF-α mice showed remodeling in alveolar and airway walls similar to what we observed in patients with COPD. Epithelial cells are able to undergo a phenotypic shift, gaining mesenchymal properties, a process in which c-Jun N-terminal kinase (JNK) signaling is involved. Therefore, we hypothesized that TNF-α induces JNK-dependent epithelial plasticity, which contributes to lung matrix remodeling. To this end, the ability of TNF-α to induce a phenotypic shift was assessed in A549, BEAS2B, and primary bronchial epithelial cells, and phenotypic markers were studied in SPC–TNF-α mice. Phenotypic markers of mesenchymal cells were elevated both in vitro and in vivo, as shown by the expression of vimentin, plasminogen activator inhibitor-1, collagen, and matrix metalloproteinases. Concurrently, the expression of the epithelial markers, E-cadherin and keratin 7 and 18, was attenuated. A pharmacological inhibitor of JNK attenuated this phenotypic shift in vitro, demonstrating involvement of JNK signaling in this process. Interestingly, activation of JNK signaling was also clearly present in lungs of SPC–TNF-α mice and patients with COPD. Together, these data show a role for TNF-α in the induction of a phenotypic shift in vitro, resulting in increased collagen production and the expression of elastin-degrading matrix metalloproteinases, and provide evidence for involvement of the TNF-α–JNK axis in extracellular matrix remodeling.

Ciliated muconodular papillary tumors (CMPTs) are rare peripheral lung lesions, characterized by papillary architecture and ciliated columnar cells admixed with mucinous cells and basal cells. They often have prominent surrounding intra-alveolar mucin, which can lead to diagnostic confusion with mucinous adenocarcinoma. Recognition of the ciliated component is the key to diagnosis of CMPT. The literature contains few reported cases to date, all occurring in East-Asian patients. Although follow-up data are limited, CMPT seems to be an indolent tumor with very good prognosis, leading some to question whether it is a reactive or hamartomatous lesion. However, a very recent molecular study has identified BRAF (40%) and EGFR (30%) alterations in CMPT, supporting a truly neoplastic process. Here for the first time, we report 4 cases of morphologically typical CMPT in western patients, occurring in 1 man (60 y) and 3 women (71 to 83 y). Interestingly, 1 case occurred in background of pronounced small airway disease with necrotizing bronchiolitis and multiple carcinoid tumorlets. We further analyzed 1 tumor using a 50 gene next-generation sequencing oncology panel that identified 2 pathogenic mutations (BRAF V600E and AKT1 E17K). Our study is the first to describe that CMPT can occur in western (non-Asian) patients. Our data confirm BRAF V600E mutation as a probable driver in a subset of these tumors, along with AKT1 mutation, which further supports that CMPT are indolent pulmonary neoplasms.