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J Autoimmun. 2017 Jul;81:120-129. doi: 10.1016/j.jaut.2017.04.006. Epub 2017 Apr 29.

NAD+ dependent deacetylase Sirtuin 5 rescues the innate inflammatory response of endotoxin tolerant macrophages by promoting acetylation of p65.

Author information

1
National Key Laboratory of Medical Immunology & Institute of Immunology, Second Military Medical University, Shanghai 200433, China.
2
National Key Laboratory of Medical Immunology & Institute of Immunology, Second Military Medical University, Shanghai 200433, China; Department of Immunology & Center for Immunotherapy, Institute of Basic Medical Sciences, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100005, China. Electronic address: caoxt@immunol.org.

Abstract

The induction and persistence of a hypo-inflammatory and immunosuppressive state in severe sepsis is commonly associated with increased risks of secondary infections and mortality. Toll-like receptor (TLR)-triggered inflammatory response of macrophages/monocytes plays an important role in determining the outcome of hyper-inflammation during the acute phase and the hypo-inflammation during immunosuppressive phase of sepsis. However, the mechanisms for controlling hypo-inflammatory response in endotoxin tolerant macrophages remain to be fully understood. Considering that metabolic control of inflammation is an emerging field and the balance between AMP/ATP and oxidized NAD+/reduced NADH is associated with inflammation and metabolism, we analyzed the level of NAD+ in TLR-triggered innate inflammatory response, and found that the decreased level of NAD+ was significantly related to the increased inflammatory cytokine production both in vivo and in vitro. By screening the expression and function of NAD+ dependent type III deacetylase Sirtuin family members, we found that SIRT5 and SIRT1/2 had opposite expression patterns and functions in macrophages. SIRT5 deficiency decreased TLR-triggered inflammation in both acute and immunosuppressive phases of sepsis. Interestingly, cytoplasmic SIRT5 counteracted the inhibitory effects of SIRT2 and enhanced the innate inflammatory responses in macrophages and even in endotoxin-tolerant macrophages by promoting acetylation of p65 and activation of NF-κB pathway. Mechanistically, SIRT5 competed with SIRT2 to interact with NF-κB p65, in a deacetylase activity-independent way, to block the deacetylation of p65 by SIRT2, which consequently led to increased acetylation of p65 and the activation of NF-κB pathway and its downstream cytokines. Our study discovered the new functions of different Sirtuin members in sepsis, indicating that targeting of Sirtuin family members at different sepsis phases can be helpful to precisely control the progression of sepsis.

KEYWORDS:

Hypo-inflammation; NF-κB; Proinflammatory cytokine; SIRT5; Sepsis; Sirtuin

PMID:
28461090
DOI:
10.1016/j.jaut.2017.04.006
[Indexed for MEDLINE]

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