The major antiinflammatory effects of glucocorticoids appear to be due largely to interaction between the activated glucocorticoid receptor and transcription factors, notably nuclear factor-kappaB (NF-kappaB) and activator protein-1, that mediate the expression of inflammatory genes. NF-kappaB switches on inflammatory genes via a process involving recruitment of transcriptional coactivator proteins and changes in chromatin modifications such as histone acetylation. This process must occur in the correct temporal manner to allow for effective inflammatory gene expression to occur. Glucocorticoids, using a similar mechanism, are also able to switch on a number of antiinflammatory genes. An important question is why glucocorticoids switch off only inflammatory genes, as they clearly do not suppress all activated genes and are well tolerated as long-term treatments. The interactions between NF-kappaB and the glucocorticoid receptor result in differing effects on histone acetylation and deacetylation. Oxidative stress due to cigarette smoke may be an important factor in inducing glucocorticoid resistance in chronic obstructive pulmonary disease and may involve changes in histone acetylation/deacetylation balance.

Cigarette smoke is the major cause of chronic obstructive pulmonary disease (COPD), a chronic inflammatory disease of the airway. The increased expression of inflammatory proteins results from enhanced gene transcription, as these mediators are induced in a cell‐specific manner. Changes in transcription depend on chromatin remodeling and the relative activities of histone acetyl‐transferases (HATs) and histone deacetylases (HDACs). We have shown that cigarette smoke reduces the expression of HDAC2 expression and HDAC activity in biopsies and alveolar macrophages. Cigarette smoke also enhanced IL‐1β–induced expression of tumor necrosis factor α (TNF‐α) by alveolar macrophages. TNF‐α release was enhanced by the HDAC inhibitor Trichostatin A and correlated significantly with HDAC activity. In addition, we show that glucocorticoid‐responsiveness is reduced in these cells and correlates with HDAC activity. Using a macrophage cell line, we show that hydrogen peroxide mimics cigarette smoke effects on HDAC activity and markedly attenuates dexamethasone inhibition of cytokine release. These results offer the first evidence for a suppressive effect of cigarette smoke on histone acetylation status. Reduced HDAC expression may account for the enhanced expression of inflammatory mediators such as GM‐CSF, IL‐8 and TNF‐α by cigarette smoke seen in lavage samples of smokers and patients with COPD. In addition, this mechanism may account for the reduced effectiveness of glucocorticoids in COPD.

U-BIOPRED cohort n=91 epithelial brushings or biopsies IL-17 High Clinical phenotype Nasal polyps Smoking Antibiotic use Epithelial Gene Expression Profile Clinical phenotype FeNO Exacerbations Gene expression shared with psoriasis IDO1 IL1B DEFB4B S100A8, S100A9 PI3 CXCL3, CXCL8 CXCL10, CCL20 Gene signature SERPINB2 POSTN CLCA1 IL-13 High T cell infiltration Neutrophilia Eosinophilia IL-17-high asthma with features of a psoriasis immunophenotype From a the Respiratory,

Large differences in COVID‐19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage were associated with low death rates in European countries. SARS‐CoV‐2 binds to its receptor, the angiotensin converting enzyme 2 (ACE2). As a result of SARS‐Cov‐2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT 1 R) axis associated with oxidative stress. This leads to insulin resistanceas well as lung and endothelial damage, two severe outcomes of COVID‐19. The nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2) is the most potent antioxidant in humans and can block the AT 1 R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are given: Kimchi in Korea, westernized foods and the slum paradox. It is proposed that fermented cabbage is a proof‐of‐concept of dietary manipulations that may enhance Nrf2‐associated antioxidant effects helpful in mitigating COVID‐19 severity.

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