Accumulation Of M2 Macrophages Research Articles

The combination of berberine and isoliquiritigenin synergistically improved adipose inflammation and obesity-induced insulin resistance.

White adipose tissue accumulation and inflammation contribute to obesity by inducing insulin resistance. Herein, we aimed to screen the synergistic components of the herbal pair Coptidis Rhizoma-Glycyrrhizae Radix et Rhizoma for the treatment of insulin resistance and explore the potential synergistic mechanisms. Enzyme-linked immunosorbent assay and quantitative PCR were used to detect expression levels of inflammatory genes in vitro and in vivo. Western blotting and immunohistochemistry were performed to detect protein levels of the insulin signaling pathway and macrophage markers. The effects on obesity-induced insulin resistance were verified using a diet-induced obesity (DIO) mouse model. Interactions between macrophage and adipocyte were assessed using a cellular supernatant transfer assay. Berberine (BBR) and isoliquiritigenin (ISL) alleviated mRNA levels and secretion of inflammatory genes in vitro and in vivo. Furthermore, BBR acted synergistically with ISL to ameliorate obesity and dyslipidemia in DIO mice. Meanwhile, the combination treatment significantly improved glucose intolerance and insulin resistance and decreased M1-macrophage accumulation and infiltration in the adipose tissue. Mechanistically, co-treatment with BBR and ISL upregulated the protein expression of the IRS1-PI3K-Akt insulin signaling pathway, enhanced glucose uptake in adipocyte, and suppressed the interaction between macrophage and adipocyte. BBR and ISL were identified as the synergistic components of the herbal pair Coptidis Rhizoma-Glycyrrhizae Radix et Rhizoma for treating insulin resistance. The synergistic combination of BBR with ISL can be a promising and effective strategy for improving obesity-induced adipose inflammation and insulin resistance.

Inhibition of NADPH oxidase 2 enhances resistance to viral neuroinflammation by facilitating M1-polarization of macrophages at the extraneural tissues

BackgroundMacrophages play a pivotal role in the regulation of Japanese encephalitis (JE), a severe neuroinflammation in the central nervous system (CNS) following infection with JE virus (JEV). Macrophages are known for their heterogeneity, polarizing into M1 or M2 phenotypes in the context of various immunopathological diseases. A comprehensive understanding of macrophage polarization and its relevance to JE progression holds significant promise for advancing JE control and therapeutic strategies.MethodsTo elucidate the role of NADPH oxidase-derived reactive oxygen species (ROS) in JE progression, we assessed viral load, M1 macrophage accumulation, and cytokine production in WT and NADPH oxidase 2 (NOX2)-deficient mice using murine JE model. Additionally, we employed bone marrow (BM) cell-derived macrophages to delineate ROS-mediated regulation of macrophage polarization by ROS following JEV infection.ResultsNOX2-deficient mice exhibited increased resistance to JE progression rather than heightened susceptibility, driven by the regulation of macrophage polarization. These mice displayed reduced viral loads in peripheral lymphoid tissues and the CNS, along with diminished infiltration of inflammatory cells into the CNS, thereby resulting in attenuated neuroinflammation. Additionally, NOX2-deficient mice exhibited enhanced JEV-specific Th1 CD4 + and CD8 + T cell responses and increased accumulation of M1 macrophages producing IL-12p40 and iNOS in peripheral lymphoid and inflamed extraneural tissues. Mechanistic investigations revealed that NOX2-deficient macrophages displayed a more pronounced differentiation into M1 phenotypes in response to JEV infection, thereby leading to the suppression of viral replication. Importantly, the administration of H2O2 generated by NOX2 was shown to inhibit M1 macrophage polarization. Finally, oral administration of the ROS scavenger, butylated hydroxyanisole (BHA), bolstered resistance to JE progression and reduced viral loads in both extraneural tissues and the CNS, along with facilitated accumulation of M1 macrophages.ConclusionIn light of our results, it is suggested that ROS generated by NOX2 play a role in undermining the control of JEV replication within peripheral extraneural tissues, primarily by suppressing M1 macrophage polarization. Subsequently, this leads to an augmentation in the viral load invading the CNS, thereby facilitating JE progression. Hence, our findings ultimately underscore the significance of ROS-mediated macrophage polarization in the context of JE progression initiated JEV infection.

CD226 promotes renal fibrosis by regulating macrophage activation and migration.

It has been found that CD226 plays an important role in regulating macrophage function, but its expression and function in macrophages during renal fibrogenesis have not been studied. Our data demonstrated that CD226 expression in macrophages was obviously upregulated in the unilateral ureteral obstruction model, while CD226 deficiency attenuated collagen deposition in renal interstitium along with fewer M1 within renal cortex and renal medulla and a lower level of proinflammatory factors compared to that of control littermates. Further studies demonstrated that Cd226-/- bone marrow-derived macrophages transferring could significantly reduce the tubular injury, collagen deposition, and proinflammatory cytokine secretion compared with that of Cd226+/+ bone marrow-derived macrophages transferring in the unilateral ureteral obstruction model. Mechanistic investigations revealed that CD226 promoted proinflammatory M1 macrophage accumulation in the kidney via suppressing KLF4 expression in macrophages. Therefore, our results uncovered a pathogenic role of CD226 during the development of chronic kidney disease by promoting monocyte infiltration from peripheral blood into the kidney and enhancing macrophage activation toward the inflammatory phenotype by suppressing KLF4 expression.

Narrow-band UVB radiation triggers diverse changes in the gene expression and induces the accumulation of M1 macrophages in human skin

BackgroundThe underlying molecular mechanisms that determine the biological effects of UVB radiation exposure on human skin are still only partially comprehended. ObjectivesOur goal is to examine the human skin transcriptome and related molecular mechanisms following a single exposure to UVB in the morning versus evening. MethodsWe exposed 20 volunteer females to four-fold standard erythema doses (SED4) of narrow-band UVB (309–313 nm) in the morning or evening and studied skin transcriptome 24 h after the exposure. We performed enrichment analyses of gene pathways, predicted changes in skin cell composition using cellular deconvolution, and correlated cell proportions with gene expression. ResultsIn the skin transcriptome, UVB exposure yielded 1384 differentially expressed genes (DEGs) in the morning and 1295 DEGs in the evening, of which the most statistically significant DEGs enhanced proteasome and spliceosome pathways. Unexposed control samples showed difference by 321 DEGs in the morning vs evening, which was related to differences in genes associated with the circadian rhythm. After the UVB exposure, the fraction of proinflammatory M1 macrophages was significantly increased at both timepoints, and this increase was positively correlated with pathways on Myc targets and mTORC1 signaling. In the evening, the skin clinical erythema was more severe and had stronger positive correlation with the number of M1 macrophages than in the morning after UVB exposure. The fractions of myeloid and plasmacytoid dendritic cells and CD8 T cells were significantly decreased in the morning but not in the evening. ConclusionsNB-UVB-exposure causes changes in skin transcriptome, inhibiting cell division, and promoting proteasome activity and repair responses, both in the morning and in the evening. Inflammatory M1 macrophages may drive the UV-induced skin responses by exacerbating inflammation and erythema. These findings highlight how the same UVB exposure influences skin responses differently in morning versus evening and presents a possible explanation to the differences in gene expression in the skin after UVB irradiation at these two timepoints.

HIIT Promotes M2 Macrophage Polarization and Sympathetic Nerve Density to Induce Adipose Tissue Browning in T2DM Mice.

Browning of white adipose tissue (WAT) is a focus of research in type 2 diabetes mellitus (T2DM) and metabolism, which may be a potential molecular mechanism for high-intensity interval training (HIIT) to improve T2DM. In this study, male C57BL/6J wild-type mice were subjected to an 8-week HIIT regimen following T2DM induction through a high-fat diet (HFD) combined with streptozotocin (STZ) injection. We found that HIIT improved glucose metabolism, body weight, and fat mass in T2DM mice. HIIT also decreased adipocyte size and induced browning of WAT. Our data revealed a decrease in TNFα and an increase in IL-10 with HIIT, although the expression of chemokines MCP-1 and CXCL14 was increased. We observed increased pan-macrophage infiltration induced by HIIT, along with a simultaneous decrease in the expression of M1 macrophage markers (iNOS and CD11c) and an increase in M2 macrophage markers (Arg1 and CD206), suggesting that HIIT promotes M2 macrophage polarization. Additionally, HIIT upregulated the expression of Slit3 and neurotrophic factors (BDNF and NGF). The expression of the sympathetic marker tyrosine hydroxylase (TH) and the nerve growth marker GAP43 was also increased, demonstrating the promotion of sympathetic nerve growth and density by HIIT. Notably, we observed macrophages co-localizing with TH, and HIIT induced the accumulation of M2 macrophages around sympathetic nerves, suggesting a potential association between M2 macrophages and increased density of sympathetic nerves. In conclusion, HIIT induces adipose tissue browning and improves glucose metabolism in T2DM mice by enhancing M2 macrophage polarization and promoting sympathetic nerve growth and density.

Inhibition of sphingosine 1-phosphate receptor 3 ameliorates bleomycin-induced pulmonary fibrosis by suppressing macrophage M2 polarization

Pulmonary fibrosis is a devastating lung disease without effective treatment options. Sphingosine-1-phosphate receptor 3 (S1pr3), a receptor for the lipid signaling molecule sphingosine-1-phosphate, has been shown to mediate the development of pulmonary fibrosis, although the underlying mechanism is not fully understood. Here, we found increased expression of S1pr3 in the lung during the process of bleomycin-induced pulmonary fibrosis in mice and specific overexpression of S1pr3 in the infiltrated M2 macrophages. We constructed LysM-Cre+/S1pr3flox/flox mice, in which S1pr3 was conditionally depleted in myeloid cells, and this depletion protected mice from bleomycin-induced lung injury and fibrosis, with reduced M2 macrophage accumulation in the lung. Increased S1pr3 expression was found in bone marrow-derived macrophages after alternatively activated by IL4 ex vivo, while loss of S1pr3 attenuated IL-4-induced M2 polarization in bone marrow-derived macrophages by repressing the PI3K/Akt-Stat3 signaling pathway. Moreover, the S1pr3 inhibitors CAY10444 and TY52156 exerted protective effects on pulmonary fibrosis in mice. Taken together, our research showed that inhibition of S1pr3 ameliorates bleomycin-induced pulmonary fibrosis by reducing macrophage M2 polarization via the PI3K/Akt-Stat3 signaling pathway, indicating that S1pr3 may be a potential target for pulmonary fibrosis treatment.

Chlorogenic acid supported strontium polyphenol networks ensemble microneedle patch to promote diabetic wound healing

Delayed or non-healing of diabetic wounds is a significant complication, often attributed to high glucose-induced M1 macrophage accumulation, impaired angiogenesis, and reactive oxygen species (ROS) buildup. Addressing this, we introduced a strontium polyphenol network microneedle patch (SrC-MPNs@MN-PP) for percutaneous drug delivery. This patch, formulated with polymer poly(γ-glutamic acid) (γ-PGA) and epsilon-poly-l-lysine (ε-PLL), incorporates strontium polyphenol networks (SrC-MPNs). The release of chlorogenic acid (CGA) from SrC-MPNs not only neutralizes ROS, but strontium ions also foster angiogenesis. Consequently, SrC-MPNs@MN-PP can ameliorate the diabetic wound microenvironment and expedite healing.

IL-27 Gene Therapy Induces Stat3-Mediated Expansion of CD11b+Gr1+ Myeloid Cells and Promotes Accumulation of M1 Macrophages in the Tumor Microenvironment.

IL-27 is a pleiotropic cytokine that exhibits stimulatory/regulatory functions on multiple lineages of immune cells and has a potential to be used as a therapeutic for cancer. We have recently demonstrated that administration of IL-27 producing adeno-associated virus (AAV-IL-27) exhibits potent inhibition of tumor growth in mouse models. In this study, we demonstrate that AAV-IL-27 treatment leads to significant expansion of CD11b+Gr1+ myeloid cells. AAV-IL-27-induced expansion of CD11b+Gr1+ cells is IL-27R-dependent and requires Stat3 signaling, but it is inhibited by Stat1 signaling. AAV-IL-27 treatment does not increase the self-renewal capacity of CD11b+Gr1+ cells but induces significant expansion of Lin-Sca1+c-Kit+ (LSK) and granulocyte-monocyte progenitor cells. Despite exhibiting significant suppression of T cells invitro, IL-27-induced CD11b+Gr1+ cells lost the tumor-promoting activity invivo and overall play an antitumor role. In tumors from AAV-IL-27-treated mice, CD11b+Gr1+ cells are largely F4/80+ and express high levels of MHC class I/II and M1 macrophage markers. Thus, IL-27 gene therapy induces Stat3-mediated expansion of CD11b+Gr1+ myeloid cells and promotes accumulation of M1 macrophages in the tumor microenvironment.

Glycyrrhetinic Acid Liposomes Encapsulated Microcapsules from Microfluidic Electrospray for Inflammatory Wound Healing

AbstractIn diabetic wound healing, M1 macrophage accumulation and elevated inflammation are prevalent issues. Intelligent delivery systems that can sustainably release antioxidizing and anti‐inflammatory ingredients are expected for effective wound healing. Herein, a novel glycyrrhetinic acid (GA) liposomes encapsulated microcapsules delivery system that has desired features for inflammatory wound repair is presented. As the bacteria could break down the alginate shells, the GA liposomes could be controllably released from the microcapsules, which promotes M2 macrophage polarization and regulate their responses in the inflammatory wound microenvironment. Based on these, it is demonstrated that the GA liposomes encapsulated microcapsules delivery system exhibits an anti‐inflammatory and immunomodulatory effect for diabetic wound healing in a full‐thickness defect model in diabetic rats. These results indicate that the immunomodulatory capabilities of the microcapsules can be unitized for efficient wound repair, and such a delivery system is valuable for clinical wound healing applications.

Local administration of liposomal-based Plekhf1 gene therapy attenuates pulmonary fibrosis by modulating macrophage polarization.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease with limited therapeutic options. Macrophages, particularly alternatively activated macrophages (M2), have been recognized to contribute to the pathogenesis of pulmonary fibrosis. Therefore, targeting macrophages might be a viable therapeutic strategy for IPF. Herein, we report a potential nanomedicine-based gene therapy for IPF by modulating macrophage M2 activation. In this study, we illustrated that the levels of pleckstrin homology and FYVE domain containing 1 (Plekhf1) were increased in the lungs originating from IPF patients and PF mice. Further functionality studies identified the pivotal role of Plekhf1 in macrophage M2 activation. Mechanistically, Plekhf1 was upregulated by IL-4/IL-13 stimulation, after which Plekhf1 enhanced PI3K/Akt signaling to promote the macrophage M2 program and exacerbate pulmonary fibrosis. Therefore, intratracheal administration of Plekhf1 siRNA-loaded liposomes could effectively suppress the expression of Plekhf1 in the lungs and notably protect mice against BLM-induced lung injury and fibrosis, concomitant with a significant reduction in M2 macrophage accumulation in the lungs. In conclusion, Plekhf1 may play a crucial role in the pathogenesis of pulmonary fibrosis, and Plekhf1 siRNA-loaded liposomes might be a promising therapeutic approach against pulmonary fibrosis.

G-MDSC-derived exosomes mediate the differentiation of M-MDSC into M2 macrophages promoting colitis-to-cancer transition

BackgroundsIn inflammatory bowel disease microenvironment, transdifferentiation of myeloid-derived suppressor cells (MDSCs) and M2 macrophage accumulation are crucial for the transition of colitis-to-cancer. New insights into the cross-talk and the underling...

Traumatic muscle injury promotes aberrant fibro-adipogenic progenitor cell population, leading to fibrosis and impaired muscle stem cell function

Skeletal muscle has an exceptional regenerative capacity that relies on the temporal activation and regulation of immune cells, fibro-adipogenic progenitors (FAPs), and muscle stem cells (MuSCs). However, following traumatic injury to skeletal muscle, such as in extensive muscle deficits caused by injury or surgery, also known as volumetric muscle loss (VML), this coordinated regenerative response is diminished, leading to fibrosis, inflammation, and chronic functional deficiencies. The goal of this study was to compare the temporal response and phenotype of key cell populations, including macrophages, FAPs, and MuSCs following critical and sub-critical VML injuries in the mouse quadriceps. We hypothesize that traumatic injury, specifically VML, drives cell phenotypic variability amongst these cell populations. Unilateral VML injuries were used to quantify cell type distribution via flow cytometry at 1, 3, and 7 days post-VML (pVML, n=4 per injury size and time point). At day 7 pVML, anti-inflammatory M2 macrophages, FAPs, and MuSCs were all present in significantly elevated numbers per tissue volume in critical (3-mm) injuries compared to sub-critical (2-mm) injuries (p<0.05). Using multi-dimensional flow cytometry analysis, a distinct sub-population of FAPs was identified in critically sized VML injuries which had larger cell content and highly expressed the β1-integrin cell-surface marker. FAPs from quadriceps at day 7 pVML (VML-FAPs) were purified using fluorescence-activated cell sorting and cultured in vitro. VML-FAPs exhibited increased proliferation, increased cell area, and showed elevated levels of β1-integrin expression. In co-culture experiments, VML-FAPs were also shown to significantly decrease the myogenic capacity of primary MuSCs by quantification of myotube formation (p<0.05). When cultured with the anti-inflammatory cytokine TGF-β1, VML-FAPs more readily differentiated down a fibroblastic lineage. Collectively, these results indicate that following traumatic injury, namely VML, there is an aberrant shift in the FAPs cell population, possibly driven by the accumulation of M2 macrophages, towards a lineage which is persistent, pro-fibrotic, and anti-myogenic. The identification of this shift in VML-FAPs will be key to the development of pro-regenerative therapeutics for VML, as success of these VML-FAP interventions will rely on the ability to downregulate the fibrotic lineage of FAPs while maintaining their traditional pro-myogenic qualities during regeneration. Furthermore, this study also provokes investigation of differing FAP phenotypes in other traumatic muscle injuries to identify possible trends or incongruencies that may exist. Funding: This work was supported by the National Institute of Health under award number R01AG072309, R01AR071708, and Department of Defense under award number W81XWH-20-1-0336. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Lean adipose tissue macrophage derived exosome confers immunoregulation to improve wound healing in diabetes

Chronic non-healing wounds, a prevalent complication of diabetes, are associated with increased mortality in diabetic patients. Excessive accumulation of M1 macrophages in diabetic wounds promotes inflammation and results in dysregulated tissue repair. Adipose tissue macrophages (ATMs) derived from healthy lean donors have the ability to improve glucose tolerance and insulin sensitivity, as well as modulate inflammation. MicroRNAs (miRs), which can be packaged into exosomes (Exos) and secreted from cells, serve as essential regulators of macrophage polarization. Here, we revealed that ATMs isolated from lean mice secrete miRs-containing Exos, which modulate macrophage polarization and promote rapid diabetic wound healing when administered to diabetes-prone db/db mice. The miRs sequence of tissue samples from wounds treated with Exos secreted by lean ATMs (ExosLean) revealed that miR-222-3p was up-regulated. Further analyses showed that inhibiting miR-222-3p using a miR inhibitor impaired the macrophage-reprogramming effect of ExosLean. In the excisional skin wound mouse model, locally inhibiting miR-222-3p disrupted healing dynamics and failed to modulate macrophage polarization. Mechanistic studies revealed a connection between miR-222-3p, Bcl2l11/Bim, an inflammatory response effector, macrophage polarization, and diabetic wound healing. In summary, ExosLean act as positive regulators of macrophage polarization by regulating miR levels in wounds and accelerating wound healing, and thus have important implications for wound management in diabetes.Graphic

Diminazene aceturate exacerbates renal fibrosis after unilateral ureteral obstruction in female mice.

Diminazene aceturate (DIZE), an angiotensin-converting enzyme 2 (ACE2) activator, exerts anti-inflammatory and antifibrotic effects in a variety of human chronic diseases. However, the role of DIZE in kidney fibrosis and the underlying mechanism remain unclear. Therefore, we investigated the effects of DIZE on the progression of renal fibrosis after unilateral ureteral obstruction (UUO), a well-established model of chronic kidney disease. C57BL/6 female or male mice were subjected to right UUO. Mice received 15 mg/kg DIZE or vehicle (saline) daily. On the 7th day after UUO, kidneys were collected for analysis of renal fibrosis (α-smooth muscle actin, phosphorylated SMAD3, transforming growth factor (TGF)-β, Masson's trichrome, and Sirius red staining), inflammation (macrophage infiltration, proinflammatory cytokines/ chemokines), apoptosis/necrotic cell death (TUNEL and periodic acid-Schiff staining), and ACE2 activity and messenger RNA (mRNA) expression. Treatment with DIZE exacerbated renal fibrosis by upregulating the profibrotic TGF-β/SMAD3 pathway, proinflammatory cytokine/chemokines (interleukin [IL]-1β, monocyte chemoattractant protein-1, IL-6, and macrophage inflammatory protein-2) levels, M2 macrophage accumulation (CD206, IL-4, IL-10, and CX3CL1), and apoptotic/necrotic cell death in the obstructed kidneys of female mice but not male mice. However, DIZE treatment had no effect on ACE2 activity or mRNA expression. DIZE exacerbates UUO-induced renal fibrosis by aggravating tubular damage, apoptosis, and inflammation through independent of angiotensin (1-7), angiotensin II levels, and ACE2 expression/activity, rather than protecting against renal fibrosis after UUO. DIZE also has powerful effects on recruiting macrophages, including the M2-polarized subtype, in female UUO mice.

The flavonoid fisetin ameliorates renal fibrosis by inhibiting SMAD3 phosphorylation, oxidative damage, and inflammation in ureteral obstructed kidney in mice.

Renal fibrosis is characterized by the accumulation of extracellular matrix and inflammatory cells and kidney dysfunction, which is a major pathway in the progression of chronic kidney disease (CKD). Accumulating evidence indicates that oxidative stress plays a critical role in the initiation and progression of CKD via proinflammatory and profibrotic signaling pathways. Fisetin (3,3',4',7-tetrahydroxyflavone) has biological activities including antioxidant, anti-inflammatory, and anti-aging effects. Therefore, we evaluated the antifibrotic effects of fisetin on unilateral ureteral obstruction (UUO)-induced kidneys. C57BL/6 female mice were subjected to right UUO and intraperitoneally injected every other day with fisetin (25 mg/kg/ day) or vehicle from 1 hour before surgery to 7 days after surgery. Kidney samples were analyzed for renal fibrosis (α-smooth muscle actin [α-SMA] expression, collagen deposition, and transforming growth factor [TGF] β1/SMAD3 signaling pathway), oxidative damage (4-HNE and 8-OHdG expression), inflammation (proinflammatory cytokine/chemokine, macrophage, and neutrophil infiltration), and apoptosis (TUNEL staining). Cultured human proximal tubule cells were treated with fisetin before TGF-β to confirm the TGF-β downstream pathway (SMAD2/3 phosphorylation). We found that fisetin treatment protected against renal fibrosis by inhibiting the phosphorylation of SMAD3, oxidative damage, inflammation, apoptotic cell death, and accumulation of profibrotic M2 macrophages in the obstructed kidneys. In cultured human proximal tubular cells, fisetin treatment inhibited TGF-β1-induced phosphorylation of SMAD3 and SMAD2. Fisetin alleviates kidney fibrosis to protect against UUO-induced renal fibrosis, and could be a novel therapeutic drug for obstructive nephropathy.

Tissue transglutaminase exacerbates renal fibrosis via alternative activation of monocyte-derived macrophages

Macrophages are important components in modulating homeostatic and inflammatory responses and are generally categorized into two broad but distinct subsets: classical activated (M1) and alternatively activated (M2) depending on the microenvironment. Fibrosis is a chronic inflammatory disease exacerbated by M2 macrophages, although the detailed mechanism by which M2 macrophage polarization is regulated remains unclear. These polarization mechanisms have little in common between mice and humans, making it difficult to adapt research results obtained in mice to human diseases. Tissue transglutaminase (TG2) is a known marker common to mouse and human M2 macrophages and is a multifunctional enzyme responsible for crosslinking reactions. Here we sought to identify the role of TG2 in macrophage polarization and fibrosis. In IL-4-treated macrophages derived from mouse bone marrow and human monocyte cells, the expression of TG2 was increased with enhancement of M2 macrophage markers, whereas knockout or inhibitor treatment of TG2 markedly suppressed M2 macrophage polarization. In the renal fibrosis model, accumulation of M2 macrophages in fibrotic kidney was significantly reduced in TG2 knockout or inhibitor-administrated mice, along with the resolution of fibrosis. Bone marrow transplantation using TG2-knockout mice revealed that TG2 is involved in M2 polarization of infiltrating macrophages derived from circulating monocytes and exacerbates renal fibrosis. Furthermore, the suppression of renal fibrosis in TG2-knockout mice was abolished by transplantation of wild-type bone marrow or by renal subcapsular injection of IL4-treated macrophages derived from bone marrow of wild-type, but not TG2 knockout. Transcriptome analysis of downstream targets involved in M2 macrophages polarization revealed that ALOX15 expression was enhanced by TG2 activation and promoted M2 macrophage polarization. Furthermore, the increase in the abundance of ALOX15-expressing macrophages in fibrotic kidney was dramatically suppressed in TG2-knockout mice. These findings demonstrated that TG2 activity exacerbates renal fibrosis by polarization of M2 macrophages from monocytes via ALOX15.

Growth differentiation factor 11 promotes macrophage polarization towards M2 to attenuate myocardial infarction via inhibiting Notch1 signaling pathway

Abstract Background Myocardial infarctions (MI) is a major threat to human health especially in people exposed to cold environment. The polarization of macrophages towards different functional phenotypes (M1 macrophages and M2 macrophages) is closely related to MI repairment. The growth differentiation factor 11 (GDF11) has been reported to play a momentous role in inflammatory associated diseases. In this study, we examined the regulatory role of GDF11 in macrophage polarization and elucidated the underlying mechanisms in MI. Methods In vivo, the mice model of MI was induced by permanent ligation of the left anterior descending coronary artery (LAD), and mice were randomly divided into the sham group, MI group, and MI+GDF11 group. The protective effect of GDF11 on myocardial infarction and its effect on macrophage polarization were verified by echocardiography, triphenyl tetrazolium chloride staining and immunofluorescence staining of heart tissue. In vitro, based on the RAW264.7 cell line, the effect of GDF11 in promoting macrophage polarization toward the M2 type by inhibiting the Notch1 Signaling pathway was validated by qRT-PCR, Western blot, and flow cytometry. Results We found that GDF11 was significantly downregulated in the cardiac tissue of MI mice. And GDF11 supplementation can improve the cardiac function. Moreover, GDF11 could reduce the proportion of M1 macrophages and increase the accumulation of M2 macrophages in the heart tissue of MI mice. Furthermore, the cardioprotective effect of GDF11 on MI mice was weakened after macrophage clearance. At the cellular level, application of GDF11 could inhibit the expression of M1 macrophage (classically activated macrophage) markers iNOS, interleukin (IL)-1β, and IL-6 in a dose-dependent manner. In contrast, GDF11 significantly increased the level of M2 macrophage markers including IL-10, CD206, arginase 1 (Arg1), and vascular endothelial growth factor (VEGF). Interestingly, GDF11 could promote M1 macrophages polarizing to M2 macrophages. At the molecular level, GDF11 significantly down-regulated the Notch1 signaling pathway, the activation of which has been demonstrated to promote M1 polarization in macrophages. Conclusions GDF11 promoted macrophage polarization towards M2 to attenuate myocardial infarction via inhibiting Notch1 signaling pathway.

Interleukin-38 suppresses abdominal aortic aneurysm formation in mice by regulating macrophages in an IL1RL2-p38 pathway-dependent manner.

Macrophages play crucial roles in abdominal aortic aneurysm (AAA) formation through the inflammatory response and extracellular matrix degradation; therefore, regulating macrophages may suppress AAA formation. Interleukin-38 (IL-38) is a member of the IL-1 family, which binds to IL-36 receptor (IL1RL2) and has an anti-inflammation effect. Because macrophages express IL1RL2, we hypothesized that IL-38 suppresses AAA formation by controlling macrophages. We assessed a C57BL6/J mouse angiotensin II-induced AAA model with or without IL-38 treatment. RAW 264.7 cells were cultured with tumor necrosis factor-α and treated with or without IL-38. Because p38 has important roles in inflammation, we assessed p38 phosphorylation in vitro and in vivo. To clarify whether the IL-38 effect depends on the p38 pathway, we used SB203580 to inhibit p38 phosphorylation. IL1RL2+ macrophage accumulation along with matrix metalloproteinase (MMP)-2 and -9 expression was observed in mouse AAA. IL-38 reduced the incidence of AAA formation along with reduced M1 macrophage accumulation and MMP-2 and -9 expression in the AAA wall. Macrophage activities including inducible nitric oxide, MMP-2, and MMP-9 production and spindle-shaped changes were significantly suppressed by IL-38. Furthermore, we revealed that inhibition of p38 phosphorylation diminished the effects of IL-38 on regulating macrophages to reduce AAA incidence, indicating the protective effects of IL-38 depend on the p38 pathway. IL-38 plays protective roles against AAA formation through regulation of macrophage accumulation in the aortic wall and modulating the inflammatory phenotype. Using IL-38 may be a novel therapy for AAA patients.

Current State of Immunotherapy and Mechanisms of Immune Evasion in Ewing Sarcoma and Osteosarcoma

We argue here that in many ways, Ewing sarcoma (EwS) is a unique tumor entity and yet, it shares many commonalities with other immunologically cold solid malignancies. From the historical perspective, EwS, osteosarcoma (OS) and other bone and soft-tissue sarcomas were the first types of tumors treated with the immunotherapy approach: more than 100 years ago American surgeon William B. Coley injected his patients with a mixture of heat-inactivated bacteria, achieving survival rates apparently higher than with surgery alone. In contrast to OS which exhibits recurrent somatic copy-number alterations, EwS possesses one of the lowest mutation rates among cancers, being driven by a single oncogenic fusion protein, most frequently EWS-FLI1. In spite these differences, both EwS and OS are allied with immune tolerance and low immunogenicity. We discuss here the potential mechanisms of immune escape in these tumors, including low representation of tumor-specific antigens, low expression levels of MHC-I antigen-presenting molecules, accumulation of immunosuppressive M2 macrophages and myeloid proinflammatory cells, and release of extracellular vesicles (EVs) which are capable of reprogramming host cells in the tumor microenvironment and systemic circulation. We also discuss the vulnerabilities of EwS and OS and potential novel strategies for their targeting.

Glucosidase inhibitor, Nimbidiol ameliorates renal fibrosis and dysfunction in type-1 diabetes

Diabetic nephropathy is characterized by excessive accumulation of extracellular matrix (ECM) leading to renal fibrosis, progressive deterioration of renal function, and eventually to end stage renal disease. Matrix metalloproteinases (MMPs) are known to regulate synthesis and degradation of the ECM. Earlier, we demonstrated that imbalanced MMPs promote adverse ECM remodeling leading to renal fibrosis in type-1 diabetes. Moreover, elevated macrophage infiltration, pro-inflammatory cytokines and epithelial‒mesenchymal transition (EMT) are known to contribute to the renal fibrosis. Various bioactive compounds derived from the medicinal plant, Azadirachta indica (neem) are shown to regulate inflammation and ECM proteins in different diseases. Nimbidiol is a neem-derived diterpenoid that is considered as a potential anti-diabetic compound due to its glucosidase inhibitory properties. We investigated whether Nimbidiol mitigates adverse ECM accumulation and renal fibrosis to improve kidney function in type-1 diabetes and the underlying mechanism. Wild-type (C57BL/6J) and type-1 diabetic (C57BL/6‐Ins2Akita/J) mice were treated either with saline or with Nimbidiol (0.40 mg kg−1 d−1) for eight weeks. Diabetic kidney showed increased accumulation of M1 macrophages, elevated pro-inflammatory cytokines and EMT. In addition, upregulated MMP-9 and MMP-13, excessive collagen deposition in the glomerular and tubulointerstitial regions, and degradation of vascular elastin resulted to renal fibrosis in the Akita mice. These pathological changes in the diabetic mice were associated with functional impairments that include elevated resistive index and reduced blood flow in the renal cortex, and decreased glomerular filtration rate. Furthermore, TGF-β1, p-Smad2/3, p-P38, p-ERK1/2 and p-JNK were upregulated in diabetic kidney compared to WT mice. Treatment with Nimbidiol reversed the changes to alleviate inflammation, ECM accumulation and fibrosis and thus, improved renal function in Akita mice. Together, our results suggest that Nimbidiol attenuates inflammation and ECM accumulation and thereby, protects kidney from fibrosis and dysfunction possibly by inhibiting TGF-β/Smad and MAPK signaling pathways in type-1 diabetes.