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

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