PGRN is involved in macrophage M2 polarization regulation through TNFR2 in periodontitis.

Progranulin (PGRN), a multifunctional growth factor, plays indispensable roles in the regulation of cancer, inflammation, metabolic diseases, and neurodegenerative diseases. Nevertheless, its immune regulatory role in periodontitis is insufficiently understood. This study attempts to explore the regulatory effects of PGRN on macrophage polarization in periodontitis microenvironment. Immunohistochemical (IHC) and multiplex immunohistochemical (mIHC) stainings were performed to evaluate the expression of macrophage-related markers and PGRN in gingival samples from periodontally healthy subjects and periodontitis subjects. RAW264.7 cells and bone marrow-derived macrophages (BMDMs) were polarized towards M1 or M2 macrophages by the addition of LPS or IL-4, respectively, and were treated with or without PGRN. Real-time fluorescence quantitative PCR (qRT-PCR), immunofluorescence staining (IF), enzyme-linked immunosorbent assay (ELISA), and flow cytometry were used to determine the expressions of M1 and M2 macrophage-related markers. Co-immunoprecipitation was performed to detect the interaction between PGRN and tumor necrosis factor receptor 2 (TNFR2). Neutralizing antibody was used to block TNFR2 to confirm the role of TNFR2 in PGRN-mediated macrophage polarization. The IHC and mIHC staining of human gingival slices showed a significant accumulation of macrophages in the microenvironment of periodontitis, with increased expressions of both M1 and M2 macrophage markers. Meanwhile, PGRN was widely expressed in the gingival tissue of periodontitis and co-expressed mainly with M2 macrophages. In vitro experiments showed that in RAW264.7 cells and BMDMs, M1 markers (CD86, TNF-α, iNOS, and IL-6) substantially decreased and M2 markers (CD206, IL-10, and Arg-1) significantly increased when PGRN was applied to LPS-stimulated macrophages relatively to LPS stimulation alone. Besides, PGRN synergistically promoted IL-4-induced M2 markers expression, such as CD206, IL-10, and Arg1. In addition, the co-immunoprecipitation result showed the direct interaction of PGRN with TNFR2. mIHC staining further revealed the co-localization of PGRN and TNFR2 on M2 macrophages (CD206+). Blocking TNFR2 inhibited the regulation role of PGRN on macrophage M2 polarization. In summary, PGRN promotes macrophage M2 polarization through binding to TNFR2 in both pro- and anti-inflammatory periodontal microenvironments.

Zhang L ，Nie F ，Zhao J ，Li S ，Liu W ，Guo H ，Yang P ... -  《Journal of Translational Medicine》

Efficacy of caerulomycin A in modulating macrophage polarization and cytokine response in a murine model of lipopolysaccharide-induced sepsis.

Sepsis is characterized by an excessive immune response. Modulation of the immune response, particularly macrophage polarization, may provide therapeutic benefit. The effects of Caerulomycin A (caeA), a known STAT1 phosphorylation inhibitor, on macrophage polarization and inflammatory markers were explored using a lipopolysaccharide (LPS)-induced sepsis mouse model. A sepsis model was established in C57BL/6 mice induced by intraperitoneal injection of LPS, and the survival rate of mice was observed after treatment with different doses of caeA to determine the optimal therapeutic dose. For in-vitro assays using the RAW264.7 macrophage cell line, the concentration of caeA that was non-toxic to cell survival was screened using the MTT assay, followed by the analyses by qRT-PCR, ELISA, Western blot and flow cytometry for M1/M2 type macrophage markers (CD86, NOS2, CD206, ARG1) and inflammatory factors (IL-1β, IL-6, TNF-α, IL-4, and IL-10) expression. In addition, the phosphorylation levels of STAT1 and STAT6 in the JAK-STAT signaling pathway were detected. The results of in-vivo experiments showed that caeA treatment (20 mg/kg) significantly increased the survival of LPS-induced septic mice and decreased the expression of M1-type macrophage markers (CD86 and NOS2) and pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) while increasing the expression of M2-type markers (CD206 and ARG1) and anti-inflammatory cytokines (IL-4 and IL-10) expression. In in-vitro experiments, 20 μM caeA effectively inhibited LPS-induced polarization of M1-type macrophages without affecting the activity of RAW264.7 cells, and caeA significantly inhibited the phosphorylation of STAT1 yet enhanced the phosphorylation level of STAT6, as detected by Western blot. CaeA effectively modulates macrophage polarization and attenuates the inflammatory response in septic mice, possibly by affecting the JAK-STAT signaling pathway. These findings support further exploration of the potential of caeA as a therapeutic agent for sepsis.

Zhang J ，Tang S 《-》

Dipyridamole Attenuates Experimental Periodontitis by Regulating M1 Macrophage Polarization via PKA/PKG Pathways.

Periodontitis is a chronic inflammatory disease initiated by dysbiosis of the local microbial community. As a non-specific phosphodiesterase inhibitor, dipyridamole features anti-oxidant and anti-inflammatory properties. This study aimed to investigate the effects of dipyridamole in an experimental rat model of periodontitis. Thirty rats were divided randomly into three groups (n = 10): non-ligature group (NL), ligature-induced periodontitis group (L), and ligature-induced periodontitis with dipyridamole administered group (L + D). All rats were euthanized on Day 14. Alveolar bone resorption was analyzed by microcomputed tomography. The mRNA levels of Il1b, Il6, tumor necrosis factor alpha (Tnfa), and inducible nitric oxide synthase (iNos) in gingival tissue were assessed by real-time quantitative polymerase chain reaction (qRT-PCR). Inflammation level, osteoclasts, and macrophages infiltration were analyzed histologically. RAW264.7 macrophages were stimulated with Porphyromonas gingivalis lipopolysaccharide (P.g. LPS) to induce M1 polarization. Different concentration of dipyridamole (0/2/10 μM) was added simultaneously. To explore the role of PKA/PKG pathways, RAW 264.7 macrophages were pretreated with 10 μM H-89 (PKA inhibitor) or 1 μM KT-5823 (PKG inhibitor), respectively. Expression of pro-inflammatory cytokines and M1 markers were detected by qRT-PCR, ELISA, and flow cytometry. Dipyridamole administration reduced alveolar bone loss, protein levels of inflammatory cytokines, and osteoclastogenesis in rats with experimental periodontitis. It also showed a tendency to decrease mRNA levels of Il1b, Il6, and Tnfa but without significant differences in gingival tissues. Moreover, the infiltration of macrophage and M1 macrophage polarization in gingival tissue of periodontitis rats were inhibited by dipyridamole administration. In addition, dipyridamole could downregulate the gene expression of Il1b and Tnfa, as well as the protein level of TNF-α, CD86, and iNOS in RAW264.7 treated with P.g. LPS. When PKA/PKG pathways were blocked, the suppression of TNF-α, CD86, and iNOS was reversed significantly. Dipyridamole alleviated experimental periodontitis in rat models by regulating M1 polarization via activation of PKA/PKG pathways and emerges as a hopeful remedy for periodontitis.

Song J ，Li X ，Abuduwaili K ，Sun Y ，Li J ，Chen D ，Chen Z ，Li Z ，Huang B ... -  《-》

Aging Affects Bone Marrow Macrophage Polarization: Relevance to Bone Healing.

Gibon E ，Loi F ，Córdova LA ，Pajarinen J ，Lin T ，Lu L ，Nabeshima A ，Yao Z ，Goodman SB ... -  《-》

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

《Jove-Journal of Visualized Experiments》