Denitrosylation of HDAC2 by targeting Nrf2 restores glucocorticosteroid sensitivity in macrophages from COPD patients
Deepti Malhotra, … , Peter Barnes, Shyam Biswal
Deepti Malhotra, … , Peter Barnes, Shyam Biswal
Published November 1, 2011; First published October 17, 2011
Citation Information: J Clin Invest. 2011;121(11):4289-4302. https://doi.org/10.1172/JCI45144.
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Research Article

Denitrosylation of HDAC2 by targeting Nrf2 restores glucocorticosteroid sensitivity in macrophages from COPD patients

Abstract

Chronic obstructive pulmonary disease (COPD), which is caused primarily by cigarette smoking, is a major health problem worldwide. The progressive decline in lung function that occurs in COPD is a result of persistent inflammation of the airways and destruction of the lung parenchyma. Despite the key role of inflammation in the pathogenesis of COPD, treatment with corticosteroids — normally highly effective antiinflammatory drugs — has little therapeutic benefit. This corticosteroid resistance is largely caused by inactivation of histone deacetylase 2 (HDAC2), which is critical for the transrepressive activity of the glucocorticoid receptor (GR) that mediates the antiinflammatory effect of corticosteroids. Here, we show that in alveolar macrophages from patients with COPD, S-nitrosylation of HDAC2 is increased and that this abolishes its GR-transrepression activity and promotes corticosteroid insensitivity. Cys-262 and Cys-274 of HDAC2 were found to be the targets of S-nitrosylation, and exogenous glutathione treatment of macrophages from individuals with COPD restored HDAC2 activity. Treatment with sulforaphane, a small-molecule activator of the transcription factor nuclear factor erythroid 2–related factor 2 (NRF2), was also able to denitrosylate HDAC2, restoring dexamethasone sensitivity in alveolar macrophages from patients with COPD. These effects of sulforaphane were glutathione dependent. We conclude that NRF2 is a novel drug target for reversing corticosteroid resistance in COPD and other corticosteroid-resistant inflammatory diseases.

Authors

Deepti Malhotra, Rajesh K. Thimmulappa, Nicolas Mercado, Kazuhiro Ito, Ponvijay Kombairaju, Sarvesh Kumar, Jinfang Ma, David Feller-Kopman, Robert Wise, Peter Barnes, Shyam Biswal

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Figure 1

S-nitrosylation of HDAC2 protein and concomitant decline in HDAC2 activity in the lungs of patients with COPD.

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S-nitrosylation of HDAC2 protein and concomitant decline in HDAC2 activ...
(A) Levels of S-nitrosylated HDAC2 in peripheral lung tissue samples from COPD and non-COPD subjects, as assessed by biotin-switch assay. (B and C) Immunoblot analysis of nuclear HDAC2 protein levels using anti-HDAC2 antibody (B) and enzymatic activity of immunoprecipitated HDAC2 (C) in peripheral lung tissue samples from COPD (n = 6) and non-COPD (n = 3) subjects. (D) Immunoblot analysis of tyrosine nitration (anti-NO-Tyr antibody) and cysteine S-nitrosylation (anti-SNO antibody) modification of immunoprecipitated HDAC2 from peripheral lung tissues of COPD (n = 6) and non-COPD (n = 3) subjects. (E and F) S-nitrosylated HDAC2 levels in alveolar macrophages from patients with COPD, as assessed by a modified biotin-switch assay. (E) Representative blot. (F) Mean band intensity for 6 patients. (G–I) Immunoblot analysis (G) and densitometric quantification (H) of total nuclear HDAC2 protein, and HDAC2 enzymatic activity (I) using immunoprecipitated HDAC2, in COPD alveolar macrophages after treatment with vehicle (VEH) or proteasome inhibitor MG132 (n = 4 per group). (C and I) Enzymatic HDAC2 activity was expressed as “μM of standard.” (J and K) HDAC2 enzymatic activity (J) and HDAC2 protein modification by immunoblot analysis (K) in COPD alveolar macrophages after treatment with GSH-e. Immunoprecipitated HDAC2 from vehicle-treated COPD macrophages was incubated with or without reducing agent DTT as a positive control. *P < 0.01, Student’s t test.