ANP and BNP Exert Anti-Inflammatory Action via NPR-1/cGMP Axis by Interfering with Canonical, Non-Canonical, and Alternative Routes of Inflammasome Activation in Human THP1 Cells

Abstract

Dysregulated inflammasome activation and interleukin (IL)-1β production are associated with several inflammatory disorders. Three different routes can lead to inflammasome activation: a canonical two-step, a non-canonical Caspase-4/5- and Gasdermin D-dependent, and an alternative Caspase-8-mediated pathway. Natriuretic Peptides (NPs), Atrial Natriuretic Peptide (ANP) and B-type Natriuretic Peptide (BNP), binding to Natriuretic Peptide Receptor-1 (NPR-1), signal by increasing cGMP (cyclic guanosine monophosphate) levels that, in turn, stimulate cGMP-dependent protein kinase-I (PKG-I). We previously demonstrated that, by counteracting inflammasome activation, NPs inhibit IL-1β secretion. Here we aimed to decipher the molecular mechanism underlying NPs effects on THP-1 cells stimulated with lipopolysaccharide (LPS) + ATP. Involvement of cGMP and PKG-I were assessed pre-treating THP-1 cells with the membrane-permeable analogue, 8-Br-cGMP, and the specific inhibitor KT-5823, respectively. We found that NPs, by activating NPR-1/cGMP/PKG-I axis, lead to phosphorylation of NLRP3 at Ser295 and to inflammasome platform disassembly. Moreover, by increasing intracellular cGMP levels and activating phosphodiesterases, NPs interfere with both Gasdermin D and Caspase-8 cleavage, indicating that they disturb non-canonical and alternative routes of inflammasome activation. These results showed that ANP and BNP anti-inflammatory and immunomodulatory actions may involve the inhibition of all the known routes of inflammasome activation. Thus, NPs might be proposed for the treatment of the plethora of diseases caused by a dysregulated inflammasome activation.

Natriuretic Peptides Regulate Prostate Cells Inflammatory Behavior: Potential Novel Anticancer Agents for Prostate Cancer

“…It has been demonstrated that inflammation increases the expression of NPs [36] and that NPR-1 is implicated in immune and inflammatory reactions [37]. ANP and BNP secretion is modulated by the inflammatory cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α [38,39]; ANP and BNP act by reducing inflammasome activation in monocytic cells [22,31,32].…”

“…We have already shown that ANP and BNP interfere with all the routes of caspase-1-inflammasome activation in monocytic cells via the modulation of multiple molecular pathways [22]. NPs capability to counteract inflammasome activation in immune cells, let us hypothesize that a different NPs and/or NPR-1 expression profile could be responsible for the dissimilar constitutive caspase-1/inflammasome activation detected in LNCaP and PC3 cells.…”

“…We found that BNP, but not ANP, diminished the protein level of the adaptor ASC (Figure 3E) and both NPs diminished the expression profile of the cytoplasmatic sensors AIM2 (Figure 3F) and NLRP3 (Figure 3G,H). We recently demonstrated that NPs, via PKG-I activation induce the phosphorylation of NLRP3 at Ser295, leading to inflammasome platform disassembly in THP1 cells [22]. To verify whether NPs can exert the same effects in prostate cancer PC3 cells, we analyzed the effect of 1 µM ANP or BNP treatment for 24 h on Ser295 phosphorylation of NLRP3 in PC3 cells.…”

“…We have recently demonstrated a powerful inhibitory action of Atrial Natriuretic Peptides (ANP) and B-Type Natriuretic Peptide (BNP) on all the routes of NLRP3-inflammasome activation in human monocytic cells via the modulation of multiple molecular pathways [22]. ANP and BNP are autocrine/paracrine/endocrine factors belonging to the family of Natriuretic Peptides (NPs).…”

Therapeutic implications of inflammasome in inflammatory bowel disease

“…The mechanism was independent of pyroptosome formation, pyroptosis, and K+ efflux for inflammasome activation. The LPS and ATP co‐stimulation of THP‐1 macrophages increased the expression of RIPK1 and activation of caspase‐8 49 . The alternative pathway of NLRP3 activation has been involved in the development of inflammation and autoimmunity 50‐52 .…”