Inhibition of protein kinase C alpha attenuates lipopolysaccharide-triggered acute lung injury by alleviating the hyperinflammatory response and oxidative stress

Yang Chen; Pengcheng Lin; Wengang Nan; Shanshan Su; Hong Zheng; Hongchang Gao; Dan Zhang; Yuping Li

doi:10.21037/atm-21-6497

Inhibition of protein kinase C alpha attenuates lipopolysaccharide-triggered acute lung injury by alleviating the hyperinflammatory response and oxidative stress

Ann Transl Med. 2022 Feb;10(3):132. doi: 10.21037/atm-21-6497.

Authors

Yang Chen^#¹, Pengcheng Lin^#¹, Wengang Nan¹, Shanshan Su¹, Hong Zheng², Hongchang Gao², Dan Zhang¹, Yuping Li¹

Affiliations

¹ Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
² Institute of Metabonomics & Medical NMR, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China.

^# Contributed equally.

Abstract

Background: The currently available treatment methods are ineffective in reducing mortality or improving outcomes in acute lung injury (ALI). The activation of protein kinase C alpha (PKCα) has recently been implicated in ALI development. We explored the potential therapeutic outcomes of PKCα inhibition in cases of ALI and to elucidate the related mechanisms.

Methods: Indexes of lung inflammation and injury were examined in lipopolysaccharide (LPS)-treated C57BL/6J mice (male) and macrophages after pretreatment with a PKCα inhibitor. Tissues were collected to assess lung injury by hematoxylin and eosin (H&E) staining. Bronchoalveolar lavage fluid was used to measure the pulmonary edema, hyperinflammatory response, and oxidative stress by bicinchoninic acid (BCA) method and enzyme-linked immunosorbent assay (ELISA). We tested the effect of PKCα inhibition on LPS-induced proliferation, cytotoxicity, oxidative damage, and the release of inflammatory cytokines in macrophages using the Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase (LDH) cytotoxicity assay kit, flow cytometry, quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and ELISA. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway related proteins were detected by Western blot, immunohistochemistry (IHC), and immunofluorescence staining.

Results: We observed that LPS upregulated PKCα phosphorylation, induced a hyperinflammatory response, and caused lung injury. However, PKCα inhibition effectively attenuated the changes caused by LPS. Moreover, we confirmed that inhibiting PKCα weakened the activity of the NF-κB pathway under LPS-induced ALI. These findings indicated that inhibition of PKCα is protective against LPS-induced hyperinflammatory response in ALI, this effect is likely to attributed to the downregulation of NF-κB signaling pathways.

Conclusions: The results showed that PKCα inhibition could attenuate ALI which may closely related to its anti-inflammatory and anti-oxidative effects.

Keywords: NF-κB pathway; Protein kinase C alpha (PKCα); acute lung injury (ALI); hyperinflammatory response; oxidative stress.