TNF and chronic obstructive pulmonary disease: Whereas compared with smokers, the upregulated mRNAs in COPD were primarily enriched in the HIF-1 and AMPK signaling pathways, the B cell receptor signaling pathway, autophagy-animal, the TNF signaling pathway, apoptosis, the JAK-STAT signaling pathway, and ferroptosis, and the downregulated mRNAs were enriched in endocytosis (Fig. 4B).