Generating rats with conditional alleles using CRISPR/Cas9

Macrophages acquire distinct phenotypes during tissue stress and inflammatory responses. Macrophages are roughly categorized into two different subsets named inflammatory M1 and anti-inflammatory M2 macrophages. We herein identified a unique pathogenic macrophage subpopulation driven by IL-23 with a distinct gene expression profile including defined types of cytokines. The freshly isolated resting mouse peritoneal macrophages were stimulated with different cytokines in vitro, the expression of cytokines and chemokines were detected by microarray, real-time PCR, ELISA and multiple colors flow cytometry. Adoptive transfer of macrophages and imiquimod-induced psoriasis mice were used. In contrast to M1- and M2-polarized macrophages, IL-23-treated macrophages produce large amounts of IL-17A, IL-22 and IFN-γ. Biochemical and molecular studies showed that IL-23 induces IL-17A expression in macrophages through the signal transducer and activator of transcription 3 (STAT3)-retinoid related orphan receptor-γ T (RORγT) pathway. T-bet mediates the IFN-γ production in IL-23-treated macrophages. Importantly, IL-23-treated macrophages significantly promote the dermatitis pathogenesis in a psoriasis-like mouse model. IL-23-treated resting macrophages express a distinctive gene expression prolife compared with M1 and M2 macrophages. The identification of IL-23-induced macrophage polarization may help us to understand the contribution of macrophage subpopulation in Th17-cytokines-related pathogenesis.

Significance: LncRNAs have been identified as regulating antiviral innate responses via different targets through various ways. Whether there is an abundant and highly conserved lncRNA in the nucleus which may regulate antiviral innate signaling through a new mechanism remains to be investigated. Here, we identify that viral infection-reduced expression of Malat1 feedback promotes IRF3-initiated type I IFN production in the innate response against viral infection. Malat1 binds to TDP43 and prevents its cleavage mediated by activated caspase-3. The cleaved TDP35 inhibits IRF3 degradation through promoting the degradation of pre-mRNA of Rbck1, an E3 ubiquitin ligase targeting IRF3. Aberrant MALAT1 reduction and IRF3 activation are found in SLE patients, providing one mechanistic explanation for why SLE patients always have type I interferonopathies.

Fatty acids (FAs) are widely involved in diverse biological functions. In mice with myeloid-specific deletion of fatty acid-binding protein 5 (FABP5), OVA-induced allergic airway inflammation (AAI) is significantly exacerbated by increasing alternatively activated macrophages (M2). Fabp5 deficiency increases IL-4-induced M2 in vitro. In macrophages, Fabp5 deletion causes significant accumulation of free long-chain unsaturated FAs, such as oleic acid, but does not cause detectable changes to other groups of FAs. Interestingly, excessive uptake of oleic acid aggravates AAI pathogenesis, with increased M2 polarization in bronchoalveolar lavage fluid. Informatics and mechanistic studies indicate that Fabp5 deficiency may reprogram metabolic pathways by enhancing FA β oxidation, tricarboxylic acid cycle, and oxidative phosphorylation, in addition to producing more ATP through activation of the PPARγ signaling pathway, reshaping macrophages in favor of M2 polarization. These results emphasize the importance of FABP5 and oleic acid in AAI, suggesting preventive and therapeutic strategies for allergic asthma.