Protection against sepsis-induced lung injury by selective inhibition of protein kinase C-δ (δ-PKC)

Abstract

Inflammation and proinflammatory mediators are activators of δ-PKC. In vitro, δ-PKC regulates proinflammatory signaling in neutrophils and endothelial and epithelial cells, cells that can contribute to lung tissue damage associated with inflammation. In this study, a specific δ-PKC TAT peptide inhibitor was used to test the hypothesis that inhibition of δ-PKC would attenuate lung injury in an animal model of ARDS. Experimental ARDS was induced in rats via 2CLP, a model of polymicrobial sepsis. Following 2CLP surgery, the δ-PKC TAT inhibitory peptide (2CLP+δ-PKC TAT in PBS) or PBS (2CLP+PBS) was administered intratracheally. Controls consisted of SO, where animals underwent a laparotomy without 2CLP. Twenty-four hours after SO or 2CLP, blood, BALF, and lung tissue were collected. 2CLP induced δ-PKC phosphorylation in the lung within 24 h. Treatment with the δ-PKC TAT inhibitory peptide significantly decreased pulmonary δ-PKC phosphorylation, indicating effective inhibition of δ-PKC activation. Plasma and BALF levels of the chemokines CINC-1 and MIP-2 were elevated in 2CLP + PBS rats as compared with SO rats. Treatment with δ-PKC TAT reduced 2CLP-induced elevations in chemokine levels in BALF and plasma, suggesting that δ-PKC modulated chemokine expression. Most importantly, intratracheal administration of δ-PKC TAT peptide significantly attenuated inflammatory cell infiltration, disruption of lung architecture, and pulmonary edema associated with 2CLP. Thus, δ-PKC is an important regulator of proinflammatory events in the lung. Targeted inhibition of δ-PKC exerted a lung-protective effect 24 h after 2CLP.

Genetic disruption of protein kinase Cδ reduces endotoxin-induced lung injury

“…In summary, the present study supports the existing findings regarding the protective influence conferred by the inhibition of PKC␦ on endothelial function (5, 6) and inflammatory response (7,19) in settings of endotoxin challenge. We show for the first time that chronic deletion and acute inactivation of PKC␦ attenuate LPS-mediated pulmonary endothelial barrier dysfunction and edema formation.…”

“…In keeping with our data, it was previously shown that intravascular administration of a cell-permeant PKC␦ inhibitor, PKC␦-TAT, attenuated edema formation in the brains of hypertensive rats via maintenance of the blood-brain barrier (33). While it was shown previously that intratracheal instillation of PKC␦-TAT peptide blunted protein levels in BAL fluid, as well as cellular infiltration into the lungs of septic rats, the route of the peptide administration suggests that the PKC␦ inhibitor was most likely affecting the alveolar epithelium and infiltrating inflammatory cells primarily (19). Thus the design and results of the current study support a critical role for PKC␦ in the pulmonary endothelium and inflammatory response to LPS-induced lung edema formation.…”

“…Kilpatrick et al (19) noted that cecal ligation-andpuncture-induced polymicrobial sepsis caused an elevation in plasma and BAL fluid levels of cytokine-induced neutrophil chemoattractant (CINC-1) and macrophage inflammatory protein (MIP-2) that was attenuated upon introduction of the PKC␦ TAT inhibitory peptide (19). In the present study, we observed no significant alteration, with genetic ablation of PKC␦, in the levels of the inflammatory cytokines IL-6, IL-10, IL-12, MCP-1, and TNF-␣ within the BAL fluid.…”

“…Tinsley et al (38) noted that PKC␦ chemical and molecular inhibition attenuated phorbol ester-induced pulmonary endothelial monolayer hyperpermeability. A recent study showed that intratracheal administration of a cell-permeant peptide that inhibits PKC␦ subcellular translocation attenuated the degree of protein and cell infiltration into the alveolar space of septic rodent lungs (19). Thus PKC␦ represents a potential therapeutic target in the treatment of acute lung injury (ALI); however, whether the protection offered by inhibition of PKC␦ in the development of ARDS is mediated through inflammatory or vascular cellular systems has yet to be fully elucidated.…”

PKCδ-IRAK1 axis regulates oxidized LDL-induced IL-1β production in monocytes

“…PKC ␦ is a serine-threonine protein kinase that can be activated by calcium and diacylglycerol and plays an important role in infl ammation (16)(17)(18). It has been shown to be involved in sepsis ( 19,20 ) and seems to mediate sepsis-induced lung injury ( 19 ). PKC ␦ also mediates high glucose-induced activation of the TLR pathway and production of infl ammatory cytokines in monocytic cells ( 21 ).…”