PPARγ In Macrophages Research Articles

Shengmai Powder regulates alveolar macrophage PPAR-γ and improves the chronic inflammatory state of chronic obstructive pulmonary disease.

This study examines the therapeutic effects of Shengmai Powder (SMP) on both in vitro and in vivo models of chronic obstructive pulmonary disease (COPD) and the underlying mechanisms. Cigarette smoke and cigarette extracts were used to create in vitro and in vivo models of COPD. ELISA was used to measure the levels of pro-inflammatory factors (IL-6, TNF-α, and IL-1β) in mouse lung tissue and alveolar macrophages. Flow cytometry assessed the phagocytic capacity of alveolar macrophage. Western blotting was used to analyze the expression of RhoA, PPARγ, IκBα, p-IκBα, P65, and p-P65 in alveolar. The results show that SMP reversed the increased levels of pro-inflammatory factors (IL-6, TNF-α, and IL-1β) in mouse lung tissue and alveolar macrophages induced by cigarette smoke and cigarette extract. SMP also restored the decreased fluorescence intensity and RhoA levels in alveolar macrophages caused by cigarette extract. Additionally, SMP increased PPARγ expression and decreased IκBα and P65 phosphorylation in alveolar macrophages exposed to cigarette extract. Also, the effects of SMP were reversed by PPARγ inhibitors. The study concluded that SMP regulates alveolar macrophage phagocytic function through the PPAR-γ/NF-κB pathway, thereby improving the chronic inflammatory state of COPD.

Lipid synthesis, triggered by PPARγ T166 dephosphorylation, sustains reparative function of macrophages during tissue repair

Macrophages may acquire a reparative phenotype that supports tissue repair and remodeling in response to tissue injury. However, the metabolic requirements underpinning this process are incompletely understood. Here, we show that posttranslational modification (PTM) of PPARγ regulates lipid synthesis in response to wound microenvironmental cues and that metabolic rewiring orchestrates function of reparative macrophages. In injured tissues, repair signaling leads to decreased macrophage PPARγ threonine 166 (T166) phosphorylation, which results in a partially active PPARγ transcriptional program comprised of increased binding activity to the regulator regions of lipid synthesis-associated genes, thereby increased lipogenesis. The accumulated lipids serve as signaling molecules, triggering STAT3-mediated growth factor expression, and supporting the synthesis of phospholipids for the expansion of the endoplasmic reticulum (ER), which is required for protein secretion. Genetic or pharmacological inhibition of PPARγ T166 phosphorylation promotes the reparative function of macrophages and facilitates tissue regeneration. In summary, our work identifies PPARγ T166-regulated lipid biosynthesis as an essential pathway for meeting the anabolic demands of the activation and function of macrophages and provides a rationale for potential therapeutic targeting of tissue repair.

Modulator Effect of AT1 Receptor Knockdown on THP-1 Macrophage Proinflammatory Activity.

We evaluated the gene expression of PPAR-γ in THP-1 macrophages using PMA (60 ng/mL). For the silencing, cells were incubated with the siRNA for 72 h and telmisartan (10 µM) was added to the medium for 24 h. After that, cells were incubated during 1 and 24 h, respectively, with Ang II (1 µM). The gene expression levels of AT1R, NF-κB, and cytokines (IL-1β, TNF-α, and IL-10) were measured by RT-qPCR. We observed that silencing of the AT1 receptor causes a decrease in the expression of mRNA of proinflammatory cytokines (IL-1β and TNF-α), NF-κB, and PPAR-γ. We conclude that AT1R gene silencing is an alternative to modulating the production of proinflammatory cytokines such as TNF-α and IL-1β via NF-κB in macrophages and having high blood pressure decrease.

Impact of exercise on uncoupling protein 1 and macrophage phenotype in mesenteric adipose tissue in an animal model of endometriosis

Endometriosis is a gynecological disorder characterized by growth of endometrial tissue outside the uterine cavity, with symptoms which may include chronic pelvic pain and infertility resulting in a decreased quality of life. Previous studies in our laboratory demonstrated that endometriosis animals have increased mesenteric adipose tissue (MAT), inflammation, and growth of implanted endometrial vesicles which are decreased by voluntary exercise. The levels of Uncoupling Protein 1 (UCP-1), a mitochondrial protein, are known to be increased by exercise in rodents, promoting thermogenesis and decreasing inflammation. Exercise can also increase expression of peroxisome proliferator-activated receptor γ (PPARγ), a member of the nuclear receptor superfamily. When activated PPARγ polarizes the macrophages into an anti-inflammatory M2 state, which can stimulate white adipose tissue beiging. We hypothesized that voluntary wheel running exercise can increase UCP-1 and M2 macrophages, decreasing MAT and endometrial vesicle size. Aim: To assess the impact of voluntary exercise on UCP-1 expression and macrophage phenotype in MAT of an animal model of endometriosis. Methods: Endometriosis was induced by implanting uterine tissue on the intestinal mesentery of female Sprague Dawley rats while control group only received sutures (SHAM). Exercise rats had access to a running wheel after surgery (ENDO-EX or SHAM-EX), while non-exercised animals didn’t (ENDO and SHAM; n=10-11/group). After sixty days, animals were sacrificed, and MAT was collected to determine CD68, UCP-1 and PPARγ expression by immunofluorescence staining. Results: Vesicles from ENDO-EX animals exhibited significantly decreased average weight (p<0.01) and smaller average total area (p<0.01) compared with the ENDO group. Endometriosis animals showed increased mesenteric adipose tissue when compared to sham group (p<0.01), which was reduced by voluntary exercise (p<0.001). Macrophage infiltration, UCP-1 and PPARγ expression increased with exercise. Conclusions: Increased UCP-1 and anti-inflammatory M2 macrophages following exercise may result in browning of MAT which can have a role in reducing the development of vesicles in the endometriosis model. These findings suggest that exercise may be a potential complementary therapeutic strategy for managing endometriosis symptoms. This work was supported by R15AT009915, R16GM149365, T32GM144896, PRI MD Summer Program and Porter Physiology Development Fellowship. This is the full abstract presented at the American Physiology Summit 2024 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.

PPARγ inhibits small airway remodeling through mediating the polarization homeostasis of alveolar macrophages in COPD

The role of Peroxisome Proliferator-Activated Receptor-γ (PPARγ) in alveolar macrophages(AMs) polarization homeostasis is closely associated with airway remodeling in COPD, but the definite mechanism remains unclear. In this study, elevated percentage of M1-type AMs and the expression of functionally cytokines were found in COPD patients and mice, which closely related to the disease severity. PPARγ was markedly up-regulated in M2-type AMs and down-regulated in M1-type AMs, and was associated with disease severity in COPD. Co-cultured with M1- or M2-type AMs promoted the epithelial-mesenchymal transition (EMT) of airway epithelial cells and the proliferation of airway smooth muscle cells. Moreover, airway remodeling and functional damage were observed in both IL4R−/− COPD mice with runaway M1-type AMs polarization and TLR4−/− COPD mice with runaway M2-type AMs polarization. Cigarette extract (CS) or lipopolysaccharide (LPS) stimulated PPARγ−/− AMs showed more serious polarization disorder towards M1, as well as CS induced PPARγ−/− COPD mice, which led to more severe airway inflammation, lung function damage, and airway remodeling. Treatment with PPARγ agonist significantly improved the polarization disorder and function activity in CS/LPS stimulated-AMs by inhibiting the JAK-STAT, MAPK and NF-κB pathways, and alleviated the airway inflammation, restored the lung function and suppressed airway remodeling in CS induced-COPD mice. Our research demonstrates that polarization homeostasis of AMs mediated by PPARγ has the protective effect in airway remodeling, and may be a novel therapeutic target for the intervention and treatment of airway remodeling in COPD.

Geraniol ameliorates acute liver failure induced by lipopolysaccharide/D-galactosamine via regulating macrophage polarization and NLRP3 inflammasome activation by PPAR-γ methylation Geraniol alleviates acute liver failure

Geraniol (Ger), a natural acyclic monoterpene alcohol, has been reported to exert protective effects through anti-inflammation in Acute liver failure (ALF). However, its specific roles and precise mechanisms underlying anti-inflammatory effects in ALF have not yet fully explored. We aimed to investigated the hepatoprotective effects and mechanisms of Ger against ALF induced by lipopolysaccharide (LPS)/D-galactosamine (GaIN). In this study, the liver tissue and serum of LPS/D-GaIN-induced mice were collected. The degree of liver tissue injury was evaluated by HE and TUNEL staining. Serum levels of liver injury markers (ALT and AST) and inflammatory factors were measured by ELISA assays. PCR and western blotting were conducted to determine the expression of inflammatory cytokines, NLRP3 inflammasome-related proteins, PPAR-γ pathway-related proteins, DNA Methyltransferases and M1/M2 polarization cytokines. Immunofluorescence staining was used to assess the localization and expression of macrophage markers (F4/80 and CD86), NLRP3 and PPAR-γ. In vitro experiments were performed in macrophages stimulated with LPS with or without IFN-γ. Purification of macrophages and cell apoptosis was analyzed using flow cytometry. We found that Ger effectively alleviated ALF in mice, specified by the attenuation of liver tissue pathological damage, inhibition of ALT, AST and inflammatory factor levels, and inactivation of NLRP3 inflammasome. Meanwhile, downregulation M1 macrophage polarization may involve in the protective effects of Ger. In vitro, Ger reduced the activation of NLRP3 inflammasome and apoptosis through regulating PPAR-γ methylation by inhibiting M1 macrophage polarization. In conclusion, Ger protects against ALF through suppressing NLRP3 inflammasome-mediated inflammation and LPS-induced macrophage M1 polarization via modulating PPAR-γ methylation.

Acetylation of PPARγ in macrophages promotes visceral fat degeneration in obesity.

Obesity is characterized by chronic, low-grade inflammation, which is driven by macrophage infiltration of adipose tissue. PPARγ is well established to have an anti-inflammatory function in macrophages, but the mechanism that regulates its function in these cells remains to be fully elucidated. PPARγ undergoes post-translational modifications (PTMs), including acetylation, to mediate ligand responses, including on metabolic functions. Here, we report that PPARγ acetylation in macrophages promotes their infiltration into adipose tissue, exacerbating metabolic dysregulation. We generated a mouse line that expresses a macrophage-specific, constitutive acetylation-mimetic form of PPARγ (K293Qflox/flox:LysM-cre, mK293Q) to dissect the role of PPARγ acetylation in macrophages. Upon high-fat diet feeding to stimulate macrophage infiltration into adipose tissue, we assessed the overall metabolic profile and tissue-specific phenotype of the mutant mice, including responses to the PPARγ agonist Rosiglitazone. Macrophage-specific PPARγ K293Q expression promotes proinflammatory macrophage infiltration and fibrosis in epididymal white adipose tissue, but not in subcutaneous or brown adipose tissue, leading to decreased energy expenditure, insulin sensitivity, glucose tolerance, and adipose tissue function. Furthermore, mK293Q mice are resistant to Rosiglitazone-induced improvements in adipose tissue remodeling. Our study reveals that acetylation is a new layer of PPARγ regulation in macrophage activation, and highlights the importance and potential therapeutic implications of such PTMs in regulating metabolism.

Regulation of the macrophage-hepatic stellate cell interaction by targeting macrophage peroxisome proliferator-activated receptor gamma to prevent non-alcoholic steatohepatitis progression in mice.

Macrophages display remarkable plasticity and can interact with surrounding cells to affect hepatic immunity and tissue remodelling during the progression of liver diseases. Peroxisome proliferator-activated receptor gamma (PPARγ) plays a critical role in macrophage maturation, polarization and metabolism. In this study, we investigated the role of PPARγ in macrophage-hepatic stellate cell (HSC) interaction during non-alcoholic steatohepatitis (NASH) development. Wild-type, Ppargfl/fl and PpargΔLyz2 mice were fed a methionine- and choline-deficient (MCD) diet to induce NASH. Depletion of macrophages was performed using an injection of gadolinium chloride intraperitoneally. PPARγ-overexpressing or PPARγ-knockout macrophages were stimulated with saturated fatty acid (SFA) and cocultured with HSCs in a conditioned medium or the transwell coculture system. Depletion of macrophages inhibited HSC activation and ameliorated NASH progression in MCD diet-fed mice. Coculturing HSCs with macrophages or culturing HSCs in a macrophage-conditioned medium-facilitated HSC activation, and this effect was magnified when macrophages were metabolically activated by SFA. Moreover, the absence of PPARγ in macrophages enhanced metabolic activation, promoting the migration and activation of HSCs through IL-1β and CCL2. In contrast, overexpression of PPARγ in macrophages obtained the opposite effects. In vivo, macrophage-specific PPARγ knockout affected the phenotype of hepatic macrophages and HSCs, involving the MAPK and NLRP3/caspase-1/IL-1β signalling pathways. Infiltrating hepatic monocyte-derived macrophages became the predominant macrophages in NASH liver, especially in PpargΔLyz2 mice, paralleling with aggravated inflammation and fibrosis. Regulating macrophage PPARγ affected the metabolic activation of macrophages and their interaction with HSCs. Macrophage-specific PPARγ may be an attractive therapeutic target for protecting against NASH-associated inflammation and fibrosis.

Lack of Nogo-B expression ameliorates PPARγ deficiency-aggravated liver fibrosis by regulating TLR4-NF-κB-TNF-α axis and macrophage polarization

Liver fibrosis is an important pathologic process in response to chronic or repetitive liver injury. It can advance to liver cirrhosis. Both peroxisome proliferator-activated receptor gamma (PPARγ) and Nogo-B play critical roles in fibrogenesis, while PPARγ is essential for the development. However, the effect of Nogo-B deficiency on the development of liver fibrosis in cell-specific PPARγ deficient mice remains unknown. In this study, hepatocyte or macrophage PPARγ deficient (hPPARγ KO or mPPARγ KO) mice, Nogo-B deficient mice, and cell-specific PPARγ plus Nogo-B double deficient (hPPARγ/Nogo-B DKO or mPPARγ/Nogo-B DKO) mice were induced liver fibrosis by CCl4 injection. We found hPPARγ KO mice showed enhanced liver fibrotic signatures compared to mPPARγ KO mice after CCl4 administration. Hepatocyte or macrophage PPARγ deficiency further enhanced CCl4-induced severe inflammation infiltration, apoptosis and M1 macrophage polarization in the liver. In contrast, Nogo-B deficiency effectively ameliorated PPARγ deficiency-aggravated liver injury and fibrosis. It ameliorated PPARγ deficiency-aggravated liver inflammation and fibrosis by suppressing hepatic stellate cell activation, TLR4-NF-κB/TNF-α signaling and M1 macrophage polarization. In conclusion, our study demonstrates that PPARγ deficiency increases susceptibility of mice to develop CCl4-induced liver injury/fibrosis, which is potently reduced by Nogo-B deficiency, indicating Nogo-B inhibition might be a therapeutic approach for liver fibrosis treatment.

Inhibition of STAT6 Activation by AS1517499 Inhibits Expression and Activity of PPARγ in Macrophages to Resolve Acute Inflammation in Mice.

Signal transducer and activator of transcription 6 (STAT6) promotes an anti-inflammatory process by inducing the development of M2 macrophages. We investigated whether modulating STAT6 activity in macrophages using AS1517499, the specific STAT6 inhibitor, affects the restoration of homeostasis after an inflammatory insult by regulating PPARγ expression and activity. Administration of AS1517499 suppressed the enhanced STAT6 phosphorylation and nuclear translocation observed in peritoneal macrophages after zymosan injection. In addition, AS1517499 delayed resolution of acute inflammation as evidenced by enhanced secretion of pro-inflammatory cytokines, reduced secretion of anti-inflammatory cytokines in PLF and supernatants from peritoneal macrophages, and exaggerated neutrophil numbers and total protein levels in PLF. We demonstrate temporal increases in annexin A1 (AnxA1) protein and mRNA levels in peritoneal lavage fluid (PLF), peritoneal macrophages, and spleen in a murine model of zymosan-induced acute peritonitis. In vitro priming of mouse bone marrow-derived macrophages (BMDM) and peritoneal macrophages with AnxA1 induced STAT6 activation with enhanced PPARγ expression and activity. Using AS1517499, we demonstrate that inhibition of STAT6 activation delayed recovery of PPARγ expression and activity, as well as impaired efferocytosis. Taken together, these results suggest that activation of the STAT6 signaling pathway mediates PPARγ expression and activation in macrophages to resolve acute inflammation.

Targeting the Macrophage: Immune Cells May Be the Key to Phthalate-Induced Liver Toxicity.

Targeting the Macrophage: Immune Cells May Be the Key to Phthalate-Induced Liver Toxicity.

The Cannabidiol Analog PECS-101 Prevents Chemotherapy-Induced Neuropathic Pain via PPARγ Receptors

Chemotherapy-induced peripheral neuropathy (CIPN) is the main dose-limiting adverse effect of chemotherapy drugs such as paclitaxel (PTX). PTX causes marked molecular and cellular damage, mainly in the peripheral nervous system, including sensory neurons in the dorsal root ganglia (DRG). Several studies have shown the therapeutic potential of cannabinoids, including cannabidiol (CBD), the major non-psychotomimetic compound found in the Cannabis plant, to treat peripheral neuropathies. Here, we investigated the efficacy of PECS-101 (former HUF-101), a CBD fluorinated analog, on PTX-induced neuropathic pain in mice. PECS-101, administered after the end of treatment with PTX, did not reverse mechanical allodynia. However, PECS-101 (1 mg/kg) administered along with PTX treatment caused a long-lasting relief of the mechanical and cold allodynia. These effects were blocked by a PPARγ, but not CB1 and CB2 receptor antagonists. Notably, the effects of PECS-101 on the relief of PTX-induced mechanical and cold allodynia were not found in macrophage-specific PPARγ-deficient mice. PECS-101 also decreased PTX-induced increase in Tnf, Il6, and Aif1 (Iba-1) gene expression in the DRGs and the loss of intra-epidermal nerve fibers. PECS-101 did not alter motor coordination, produce tolerance, or show abuse potential. In addition, PECS-101 did not interfere with the chemotherapeutic effects of PTX. Thus, PECS-101, a new fluorinated CBD analog, could represent a novel therapeutic alternative to prevent mechanical and cold allodynia induced by PTX potentially through the activation of PPARγ in macrophages.

Itaconate and leptin affecting PPARγ in M2 macrophages: A potential link to early-onset colorectal cancer

BackgroundAlong with the rising incidence of obesity, there has been an increase in patients diagnosed with early-onset colorectal cancer (<50 years old). In colorectal cancer, worse patient survival is associated with certain cytokine expression and downregulation of peroxisome proliferator activated receptor gamma expression. The effects of the obesity hormone leptin and macrophage-specific metabolite itaconate on these mechanisms are poorly understood. We investigated their impact on peroxisome proliferator activated receptor gamma and macrophage cytokine expression in vitro. MethodsM2-like macrophages were treated with either leptin, 4-octyl itaconate, or dimethyl itaconate in a dose- and time-dependent manner. Gene expression after treatment with 4 doses (D1-4) of each compound was analyzed at 4 time points (3, 6, 18, and 24 hours). ResultsPeroxisome proliferator activated receptor gamma was downregulated after 4-octyl itaconate treatment at 18 hours (FC -32.67, P ≤ .001). Interleukin-8 was upregulated after leptin and dimethyl itaconate treatment at 6 hours (FC 26.35 at D4, P ≤ .001, and FC 23.26 at D3, P = .006). Dimethyl itaconate upregulated IL-1β at 24 hours (FC 18.00 at D4, P ≤ .001). Tumor necrosis factor-α showed maximum downregulation after 4-octyl itaconate at 18 hours (FC -103.25 at D4, P ≤ .001). ConclusionsItaconate downregulates peroxisome proliferator activated receptor gamma as a tumor-suppressing factor and upregulates anti-inflammatory cytokines in M2-like macrophages. Itaconate provides a link between obesity and colorectal cancer and may be a key regulator in early-onset colorectal cancer.

Candida albicans Induces Foaming and Inflammation in Macrophages through FABP4: Its Implication for Atherosclerosis.

Atherosclerosis is a chronic degenerative disorder characterized by lipid-dense plaques and low-grade inflammation affecting arterial walls. Foamy macrophages are important in the formation of atherosclerotic plaques and the induction of low-grade inflammation. The presence of lipid-laden macrophages has occurred in infections caused by opportunistic pathogens. Candida albicans is the major cause of candidiasis in immunocompromised patients, including those with diabetes mellitus. However, the role played by C. albicans in macrophage foaming and the associated inflammation is poorly understood. We investigated whether C. albicans induces foaming along with inflammation in macrophages and, if so, by which mechanism(s). We incubated THP-1 macrophages with heat-killed C. albicans (HKCA). HKCA-induced lipid accumulation in macrophages along with increased expression of inflammatory markers, including CD11b and CD11c or expression and secretion of IL-1β. HKCA also increased the expression of PPARγ, CD36, and FABP4 in macrophages. Mechanistically, we found that the foamy and inflammatory macrophage phenotype induced by HKCA requires FABP4 because disruption of FABP4 in macrophages either by chemical inhibitor BMS309404 or small interfering RNA (siRNA) abrogated foam cell formation and expression of inflammatory markers CD11b, CD11c, and IL-1β. Furthermore, HKCA-treated macrophages displayed high expression and secretion of MMP-9. Inhibition of FABP4 resulted in suppression of HCKA-induced MMP-9 production. Overall, our results demonstrate that C. albicans induces foam cell formation, inflammation, and MMP-9 expression in macrophages via the upregulation of FABP4, which may constitute a novel therapeutic target for treating C. albicans-induced atherosclerosis.

Characterization of inflammatory changes in the breast cancer associated adipose tissue and comparison to the unaffected contralateral breast

BackgroundAdipose tissue has emerged as an important window into cancer pathophysiology, revealing potential targets for novel therapeutic interventions. The goal of this study was to compare the breast adipose tissue (BrAT) immune milieu surrounding breast carcinoma and contralateral unaffected breast tissue obtained from the same patient. Materials and methodsPatients undergoing bilateral mastectomy for unilateral breast cancer were enrolled for bilateral BrAT collection at the time of operation. After BrAT was processed, adipocyte and stromal vascular fraction (SVF) gene expression was quantified by PCR. SVF cells were also processed for flow cytometric immune cell characterization. ResultsTwelve patients underwent bilateral mastectomy for unilateral ductal carcinoma. BrAT adipocyte CXCL2 gene expression trended higher in the tumor-affected breast as compared to the unaffected breast. Macrophage MCP-1 and PPARγ gene expression also tended to be higher in the tumor-affected breasts. T cell gene expression of FOXP3 (p = 0.0370) were significantly greater in tumor-affected breasts than unaffected breasts. Affected BrAT contained higher numbers of Th2 CD4+ cells (p = 0.0165) and eosinophils (p = 0.0095) while trending towards increased macrophage and lower Th1 CD4+ cells infiltration than tumor-affected BrAT. ConclusionThis preliminary study aimed to identify the immunologic environment present within BrAT and is the first to directly compare this in individual patients’ tumor-associated and unaffected BrAT. These findings suggest that cancer-affected BrAT had increased levels of T cell specific FOXP3 and higher levels of anti-inflammatory/regulatory cells compared to the contralateral BrAT.

Voluntary Exercise Modulates Neuroimmune Response in Colonic Inflammation Induced by Endometriosis

Endometriosis is a complex gynecological disease characterized by the growth of endometrial tissue outside of the uterine cavity. Some symptoms that are prevalent in women with endometriosis are dysmenorrhea, infertility, pelvic pain, and gastrointestinal symptoms (GI). Among the GI symptoms, women with endometriosis experience painful bowel movements, diarrhea, constipation, and bloating similar to irritable bowel syndrome (IBS). Enteric glial cells (EGC), when reactive, are known to play a role in the inflammation of IBS. Reactive EGC are also involved in the polarization of macrophages to a proinflammatory phenotype; while exercise is known to promote activation of PPARγ, a nuclear receptor known for its anti-inflammatory activity, which is expressed in anti-inflammatory macrophages. We hypothesize that exercise can reduce endometriosis-induced expression of the glial fibrillary acidic protein (GFAP) and S100B, markers of reactive enteric gliosis; and promote expression of PPARγ in colonic macrophages. Methods Three groups of female Sprague Dawley rats were used: Sham Control (n=4), Endo Control (n=5), and Endo Exercise (n=5). Endometriosis was induced by suturing 4 pieces of autologous uterine tissue from the right uterine horn on the intestinal mesentery, while the Sham group only received the sutures without implants. After surgery Endo Exercise group was exposed to voluntary wheel running for 60 days, while control groups were individually housed in standard cages. On Day 60 we sacrificed the animals, examined them for endometriosis development, assessed colonic macroscopic score, and collected a piece of distal colon. We performed double immunofluorescence staining using GFAP/S100B and CD68/PPARγ antibodies, respectively, on slides containing formalin-fixed paraffin-embedded colonic tissue. Results After normalizing the mean fluorescent intensity (MFI) to DAPI, we found that the Endo Control group has a significant increase in GFAP MFI (0.57±0.06; p<0.01) compared to Sham Control (0.32±0.03), which was reduced significantly by exercise (0.38±0.01; p<0.05). Similarly, exercise significantly decreased S100B MFI (0.67±0.06; p<0.05) compared to Endo Control (1.34±0.16), although Endo Control was not significantly higher than Sham Control (0.94±0.20). For CD68/PPARγ, we found that Endo Exercise increased significantly the percentage of macrophages expressing PPARγ (88.43±3.45%; p<0.05) compared to Endo Control (51.14±10.44%). Endo Control had significantly higher macroscopic colonic damage (2.04±0.41; p<0.01) compared to Sham Control (0.26±0.14) and Endo Exercise (0.38±0.12). Conclusions These results show that endometriosis induces colonic inflammation and enteric reactive gliosis, while exercise intervention restores gut homeostasis, possibly through the increase of anti-inflammatory macrophages expressing PPARγ. Altogether, these results suggest exercise may prove beneficial to improve endometriosis-induced GI symptoms.

Convallatoxin Promotes M2 Macrophage Polarization to Attenuate Atherosclerosis Through PPARγ-Integrin αvβ5 Signaling Pathway.

IntroductionAs the primary immune cells, macrophages play a key role in atherosclerotic progression. M2 macrophage polarization has been reported to promote tissue repair and attenuate plaque formation upon the expression of anti-inflammatory factors. Convallatoxin (CNT) is a natural cardiac glycoside with anti-inflammatory pharmacological properties. However, whether CNT protects against atherosclerosis (AS) and underlying mechanisms is unknown. This work was designed to explore the potential effects of CNT on atherosclerosis.MethodsIn this study, Apolipoprotein E deficiency (ApoE−/-) mice fed with high-fat diet were established, and CNT (50 or 100 μg/kg) were intragastrically administrated for 12 weeks every day. In vitro, RAW264.7 macrophages stimulated with ox-LDL were treated with CNT (50 or 100 nM) for 24 h. The specific PPARγ antagonist, GW9662, was used to block the PPARγ signaling pathway in vitro. Then, the atherosclerotic lesions, macrophage polarization markers, inflammatory cytokines and PPARγ signaling pathway were examined in further examinations.ResultsOur results showed that the atherosclerotic lesions were reduced by CNT, as demonstrated by the downregulation of serum lipid level and aortic plaque area in AS mice. Furthermore, we found that CNT treatment promoted the expression of M2 macrophage markers (Arg1, Mrc1, Retnla and Chi3l3), and decreased the levels of pro-inflammatory cytokines (IL-6 and TNF-α), accompanied by the increase of anti-inflammatory factor (IL-10) in aortic vessels of AS mice. In ox-LDL-induced RAW264.7 cells, CNT administration also facilitated macrophages polarizing towards M2 subtype and inhibited inflammatory responses. Furthermore, both the in vivo and in vitro experiments showed CNT could increase the expression of PPARγ, Integrin αv and Integrin β5, and GW9662 could block CNT-induced M2 macrophage polarization.ConclusionTaken together, these data suggest that CNT may promote M2 macrophage polarization to exert an anti-atherosclerotic effect, partially through activating PPARγ-Integrin αvβ5 signaling pathway.

Relationship between peroxisome proliferator-activated receptor-γ mRNA expression and intracranial aneurysm rupture

It has been reported that the normal adults can suffer from an intracranial aneurysm (IA) that might present the risk of rupture and cause the subarachnoid hemorrhage. Peroxisome proliferator-activated receptor-γ (PPAR-γ) as a nuclear hormone receptor has been identified to involve in the progress of the formation and rupture of IAs. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect PPAR-γmRNA expression in the macrophages of the patients with IAs. The information including fasting blood glucose (FBG), interleukin-6 (IL-6), and systolic blood pressure (SBP) were collected. The aneurysm parameters of all the participants were obtained through the cerebral angiography. Establishing the receiver-operating characteristic curve (ROC curve) evaluated the clinical significances of PPAR-γmRNA for IAs rupture. In this study, we observed that the rupture of IAs was caused by the maximum height of aneurysm ⩾7 mm, the location of aneurysm in posterior communicating artery (PCOM) or anterior communicating artery (ACOM), and the increase of aneurysm size ratio (SR). The levels of SBP and IL-6 in the rupture group were higher than those in the unrupture group, and PPAR-γmRNA expression in the rupture group was also significantly reduced. In addition, heavy drinking was statistically significant between the ruptured and unruptured groups. There was no significant difference in serum FBG level between the two groups. The evidences of this study showed that PPAR-γmRNA was negatively correlated with SBP, SR, and IL-6 levels in rupture group, respectively. The AUC of PPAR-γmRNA in ROC curve was 0.867, indicating that the change of PPAR-γmRNA level had obvious effect on IAs rupture. The aim of this study was to evaluate the potential of PPAR-γ in macrophages to prevent IAs rupture.

Tributyltin triggers lipogenesis in macrophages via modifying PPARγ pathway.

Tributyltin (TBT), a bioaccumulative and persistent environmental pollutant, has been proposed as a metabolism disruptor and obesogen through targeting peroxisome proliferator-activated receptor gamma (PPARγ) receptor pathway. However, it remains unknown whether this biological effect occurs in macrophage, a cell type which cooperates closely with hepatocytes and adipocytes to regulate lipid metabolism. This study for the first time investigated the effect of TBT on PPARγ pathway in macrophages. Our results indicated that nanomolar levels of TBT was able to strongly activate PPARγ in human macrophages. TBT treatment also markedly increased the intracellular lipid accumulation, and enhanced the expression of lipid metabolism-related genes in macrophages, while these effects were all significantly down-regulated in PPARγ-deficient macrophages, confirming the involvement of PPARγ in TBT-induced lipogenesis. Next, a mouse model that C57BL/6 mice were orally exposed to TBT with the doses (250 and 500μg/kg body weight) lower than NOAEL (no observed adverse effect level) was used to further investigate the invivo mechanisms. And the invivo results were consistent with cellular assays, confirming the induction of PPARγ and the increased expression of lipogenesis-regulating and lipid metabolism-related genes by TBT invivo. In conclusion, this study not only provided the first evidence that TBT stimulated lipogenesis, activated PPARγ and related genes in human macrophages, but also provided insight into the mechanism of TBT-induced metabolism disturbance and obesity through targeting PPARγ via both invitro cellular assays and invivo animal models.

Cortisol Metabolism in Carp Macrophages: A Role for Macrophage-Derived Cortisol in M1/M2 Polarization.

Macrophages are crucial not only for initiation of inflammation and pathogen eradication (classically polarized M1 macrophages), but also for inflammation inhibition and tissue regeneration (alternatively polarized M2 macrophages). Their polarization toward the M1 population occurs under the influence of interferon-γ + lipopolysaccharide (IFN-γ + LPS), while alternatively polarized M2 macrophages evolve upon, e.g., interlukin 4 (IL-4) or cortisol stimulation. This in vitro study focused on a possible role for macrophage-derived cortisol in M1/M2 polarization in common carp. We studied the expression of molecules involved in cortisol synthesis/conversion from and to cortisone like 11β-hydroxysteroid dehydrogenase type 2 and 3. (11β-HSD2 and 3) and 11β-hydroxylase (CYP11b), as well as the expression of glucocorticoid receptors (GRs) and proliferator-activated receptor gamma (PPARγ) in M1 and M2 macrophages. Lastly, we analyzed how inhibition of these molecules affect macrophage polarization. In M1 cells, upregulation of gene expression of GRs and 11β-HSD3 was found, while, in M2 macrophages, expression of 11β-hsd2 was upregulated. Moreover, blocking of cortisol synthesis/conversion and GRs or PPARγ induced changes in expression of anti-inflammatory interleukin 10 (IL-10). Consequently, our data show that carp monocytes/macrophages can convert cortisol. The results strongly suggest that cortisol, via intracrine interaction with GRs, is important for IL-10-dependent control of the activity of macrophages and for the regulation of M1/M2 polarization to finally determine the outcome of an infection.