KLF9 deficiency protects the heart from inflammatory injury triggered by myocardial infarction

Age-Associated KLF9 Enhances the Inflammatory Response of Alveolar Macrophages Via Regulating TLR2 Expression

Staphylococcus aureus pneumonia is a severe infection in infant and young children. Toll-like receptor 2 (TLR2)-mediated inflammation plays essential roles in S. aureus pneumonia. Krueppel-like factor 9 (KLF9) is a transcriptional factor participating in multiple cellular aspects including inflammation. In this study, the potential roles of KLF9 in S. aureus pneumonia were evaluated. The expression of KLF9 in peripheral blood mononuclear cells (PBMCs) from healthy donors with different ages and in alveolar macrophages from mice with different ages was measured. Pam3CK4-induced expression of inflammatory cytokines was compared in alveolar macrophages from young and old mice and in wild-type (WT) and KLF9-deficient macrophages. The survival rate, body weight loss, lung pathology were compared between WT and KLF9-deficient mice after S. aureus infection. The TLR2 expression was compared between WT and KLF9-deficient macrophages after Pam3CK4 treatment. Decreased expression of KLF9 was detected in PBMCs from elder donor and in macrophages from old mice. Impaired expression of pro-inflammatory cytokines was observed in macrophages from old mice and KLF9-deficient macrophages after Pam3CK4 treatment. KLF9-deficient mice had elevated survival rate, decreased lung injury after S. aureus infection. Decreased expression of TLR2 was detected in KLF9-deficient macrophages and overexpression of TLR2 rescued the impaired expression of inflammatory cytokines in KLF9-deficient macrophages. KLF9 regulated inflammatory responses in macrophages through TLR2.

Prdx6 Regulates Nlrp3 Inflammasome Activation-Driven Inflammatory Response in Lens Epithelial Cells

The continuum of antioxidant response dysregulation in aging/oxidative stress-driven Nlrp3 inflammasome activation-mediated inflammatory response is associated with age-related diseases. Peroxiredoxin (Prdx) 6 is a key antioxidant that provides cytoprotection by regulating redox homeostasis. Herein, using lens epithelial cells (LECs) derived from the targeted inactivation of Prdx6 gene and aging lenses, we present molecular evidence that Prdx6-deficiency causes oxidative-driven Nlrp3 inflammasome activation, resulting in pyroptosis in aging/redox active cells wherein Prdx6 availability offsets the inflammatory process. We observed that Prdx6-/- and aging LECs harboring accumulated reactive oxygen species (ROS) showed augmented activation of Nlrp3 and bioactive inflammatory components, like Caspase-1, IL-1β, ASC and Gasdermin-D. Similar to lipopolysaccharide treatment, oxidative exposure led to further ROS amplification with increased activation of the Nlrp3 inflammasome pathway. Mechanistically, we found that oxidative stress enhanced Kruppel-like factor 9 (Klf9) expression in aging/Prdx6-/- mLECs, leading to a Klf9-dependent increase in Nlrp3 transcription, while the elimination of ROS by the delivery of Prdx6 or by silencing Klf9 prevented the inflammatory response. Altogether, our data identify the biological significance of Prdx6 as an intrinsic checkpoint for regulating the cellular health of aging or redox active LECs and provide opportunities to develop antioxidant-based therapeutic(s) to prevent oxidative/aging-related diseases linked to aberrant Nlrp3 inflammasome activation.