Macrophage Polarization and Functions in Pathogenesis of Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD), the major leading cause of mortality worldwide, is a progressive and irreversible respiratory condition characterized by peripheral airway and lung parenchymal inflammation, accompanied by fibrosis, emphysema, and airflow limitation, and has multiple etiologies, including genetic variance, air pollution, and repetitive exposure to harmful substances. However, the precise mechanisms underlying the pathogenesis of COPD have not been identified. Recent multiomics-based evidence suggests that the plasticity of alveolar macrophages contributes to the onset and progression of COPD through the coordinated modulation of numerous transcription factors. Therefore, this review focuses on understanding the mechanisms and functions of macrophage polarization that regulate lung homeostasis in COPD. These findings may provide a better insight into the distinct role of macrophages in COPD pathogenesis and perspective for developing novel therapeutic strategies targeting macrophage polarization.

Analysis of particulate matter-induced alteration of genes and related signaling pathways in the respiratory system.

Airborne particulate matter (PM) is a global environmental risk factor threatening human health and is a major cause of cardiovascular and respiratory disease-associated death. Current studies on PM exposure have been limited to large-scale cohort and epidemiological investigations, emphasizing the need for detailed individual-level studies to uncover specific differentially expressed genes and their associated signaling mechanisms. Herein, we revealed that PM exposure significantly upregulated inflammatory and immune responses, such as cytokine-mediated signaling pathways, complement system, and the activation and migration of immune cells in gene set enrichment analysis of our RNA sequencing (RNAseq) data. Remarkably, we discovered that the broad gene expression and signaling pathways mediated by macrophages were predominantly expressed in the respiratory system following PM exposure. Consistent with these observations, individual PMs, classified by aerodynamic size and origin, significantly promoted macrophage recruitment to the lungs in the mouse lung inflammation model. Additionally, we confirmed that RNAseq observations from the respiratory system were reproduced in murine bone marrow-derived macrophages and the alveolar macrophage cell line MH-S after individual PM exposure. Our findings demonstrated that PM exposure augmented broad inflammatory and immune responses in the respiratory system and suggested the reinforcement of global strategies for reducing particulate air pollution to prevent respiratory diseases and their exacerbation.

Pediococcus pentosaceus KF159 alleviates house dust mite-induced atopic dermatitis by promoting IL10 production and regulatory T cell induction.

Atopic dermatitis (AD) is a chronic immune disease that requires long-term management owing to its relative ease of recurrence. However, steroid treatment is limited owing to the side effects. Therefore, research on therapeutics with proven safety is required. Here, we evaluated the anti-allergic activity of the probiotic strain Pediococcus pentosaceus KF159 (PPKF159) with an ex vivo mouse model sensitized with ovalbumin (OVA) and a mouse model of AD induced by house dust mites. Changes in pathological symptoms were confirmed based on the clinical status of the AD-induced lesion site and the levels of T helper type 2 (Th2)-derived cytokines and immunoglobulin E (IgE). In addition, cell-mediated responses and related mechanisms were elucidated using various kinds of primary cells including splenocytes, mesenteric lymph nodes, Peyer's patch, and bone marrow-derived dendritic cells (BMDCs) in vitro and ex vivo. Oral administration of PPKF159 alleviated AD-like clinical symptoms such as erythema, edema, hemorrhage, and increased tissue thickness, and suppressed the production of Th2-associated cytokines and serum IgE while increasing T helper type 1 (Th1)-mediated cytokine production. PPKF159 induced tolerogenic dendritic cells (tol-DCs) by increasing the expression of ICOS-L, PD-L1, and IDO which were closely related to Treg induction in PPKF159-treated BMDCs. In addition, BMDCs and naive T cells co-cultured in the presence of PPKF159 had elevated IL10 production and increased proportions of CD4+CD25+Foxp3+ Tregs compared to the absence of PPKF159. This study showed that PPKF159 relieved AD-like clinical symptoms, modulated the Th1/Th2 immune balance, and inhibited IgE production in a mouse AD model. PPKF159 induced the transformation of dendritic cells into tolerogenic versions. These induced tol-DCs directly enhanced the production of IL10 or improved the secretion of IL10 through the induction of CD4+CD25+Foxp3+ Treg cells, thereby improving AD. These results suggest that PPKF159 can be applied as a functional food material for the treatment and prevention of AD.

Reactive Oxygen Species and Strategies for Antioxidant Intervention in Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is a life-threatening pulmonary condition characterized by the sudden onset of respiratory failure, pulmonary edema, dysfunction of endothelial and epithelial barriers, and the activation of inflammatory cascades. Despite the increasing number of deaths attributed to ARDS, a comprehensive therapeutic approach for managing patients with ARDS remains elusive. To elucidate the pathological mechanisms underlying ARDS, numerous studies have employed various preclinical models, often utilizing lipopolysaccharide as the ARDS inducer. Accumulating evidence emphasizes the pivotal role of reactive oxygen species (ROS) in the pathophysiology of ARDS. Both preclinical and clinical investigations have asserted the potential of antioxidants in ameliorating ARDS. This review focuses on various sources of ROS, including NADPH oxidase, uncoupled endothelial nitric oxide synthase, cytochrome P450, and xanthine oxidase, and provides a comprehensive overview of their roles in ARDS. Additionally, we discuss the potential of using antioxidants as a strategy for treating ARDS.

Artemisia gmelinii Extract Attenuates Particulate Matter-Induced Neutrophilic Inflammation in a Mouse Model of Lung Injury.

Particulate matter (PM) induces and augments oxidative stress and inflammation, leading to respiratory diseases. Although Artemisia gmelinii Weber ex Stechm has antioxidant and anti-inflammatory effects, there are no reports on whether Artemisia gmelinii extract (AGE) regulates lung inflammation in a PM-induced model. Thus, we investigated the protective effects of AGE using a PM-induced mouse lung inflammation model. AGE significantly decreased the expression of inflammatory chemokines, neutrophil extracellular trap formation, and the total number of inflammatory cells in the bronchoalveolar lavage fluid (BALF). Furthermore, AGE attenuated lung inflammation through the suppression of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathway, while promoting the nuclear factor erythroid-2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) signaling pathway in lung tissues. Concordant with these observations, AGE suppressed inflammatory cytokines, chemokines, reactive oxygen species, NETosis, myeloperoxidase, and neutrophil elastase by decreasing the mRNA expression of High mobility group box 1, Runt-related transcription factor 1, and Kruppel-like factor 6 in differentiated HL-60 cells. In summary, our data demonstrated that AGE suppresses PM-induced neutrophil infiltration, lung damage, and pulmonary inflammation by suppressing NF-κB/MAPK signaling pathways and enhancing the NRF2/HO-1 signaling pathway. These findings suggest that AGE administration is an effective approach for preventing and treating PM-induced respiratory inflammation.

Bulb of Lilium longiflorum Thunb Extract Fermented with Lactobacillus acidophilus Reduces Inflammation in a Chronic Obstructive Pulmonary Disease Model.

Chronic obstructive pulmonary disease (COPD), one of the leading causes of death worldwide, is caused by repeated exposure to harmful matter, such as cigarette smoke. Although Lilium longiflorum Thunb (LLT) has anti-inflammatory effects, there is no report on the fermented LLT bulb extract regulating lung inflammation in COPD. Thus, we investigated the protective effect of LLT bulb extract fermented with Lactobacillus acidophilus 803 in COPD mouse models induced by cigarette smoke extract (CSE) and porcine pancreas elastase (PPE). Oral administration of the fermented product (LS803) suppressed the production of inflammatory mediators and the infiltration of immune cells involving neutrophils and macrophages, resulting in protective effects against lung damage. In addition, LS803 inhibited CSE- and LPS-induced IL-6 and IL-8 production in airway epithelial H292 cells as well as suppressed PMA-induced formation of neutrophil extracellular traps in HL-60 cells. In particular, LS803 significantly repressed the elevated IL-6 and MIP-2 production after CSE and LPS stimulation by suppressing the activity of the nuclear factor kappa-light-chain-enhancer of activated B (NFκB) in mouse peritoneal macrophages. Therefore, our results suggest that the fermented product LS803 is effective in preventing and alleviating lung inflammation.

Camellia sinensis L. Alleviates Pulmonary Inflammation Induced by Porcine Pancreas Elastase and Cigarette Smoke Extract.

Cigarette smoke (CS) is the major factor in the development of chronic obstructive pulmonary disease (COPD), the third leading cause of death worldwide. Furthermore, although Camellia sinensis (CN) has been known as an anti-inflammatory material, the effect of CN has not yet been known on pulmonary inflammation in COPD. Thus, we investigated the protective effects of Camellia sinensis L. extract (CLE) against pulmonary inflammation in porcine pancreas elastase (PPE) and a cigarette smoke extract (CSE)-induced COPD mouse model. Oral administration of CLE suppressed the symptoms such as infiltration of immune cells, cytokines/chemokines secretion, mucus hypersecretion, and injuries of the lung parenchyma. Increased inflammatory responses in COPD are mediated by various immune cells such as airway epithelial cells, neutrophils, and alveolar macrophages. Thus, we investigated the effect and mechanisms of CLE in H292, HL-60, and MH-S cells. The CLE inhibited the expression of IL-6, IL-8, MUC5AC and MUC5B on CSE/LPS-stimulated H292 cells and also suppressed the formation of neutrophil extracellular traps and secretion of neutrophil elastase by inhibiting reactive oxygen species in PMA-induced HL-60 cells. In particular, the CLE suppressed the release of cytokines and chemokines caused by activating the nuclear factor kappa-light-chain-enhancer of activated B via the activation of nuclear factor erythroid-2-related factor 2 and the heme oxygenase-1 pathway in CSE/LPS-stimulated MH-S cells. Therefore, we suggest that the CLE administration be the effective approach for treating or preventing chronic pulmonary diseases such as COPD induced by CS.

Artemisia gmelinii Attenuates Lung Inflammation by Suppressing the NF-κB/MAPK Pathway.

Cigarette smoke (CS) is the main cause of chronic obstructive pulmonary disease (COPD), and continuous CS exposure causes lung inflammation and deterioration. To investigate the protective effects of Artemisia gmelinii against lung inflammation in this study, cigarette smoke extract (CSE)/lipopolysaccharide (LPS)-treated alveolar macrophages (AMs) and mice stimulated with CSE/porcine pancreas elastase (PPE) were used. Artemisia gmelinii ethanol extract (AGE) was effective in decreasing the levels of cytokines, chemokine, inducible nitric oxide synthase, and cyclooxygenase-2 by inhibiting mitogen-activated protein (MAP) kinases/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in AMs. Additionally, oral administration of AGE suppressed inflammatory cells' infiltration and secretion of inflammatory cytokines, chemokines, matrix metallopeptidase 9, and neutrophil extracellular traps in bronchoalveolar lavage fluid from the COPD model. Moreover, the obstruction of small airways, the destruction of the lung parenchyma, and expression of IL-6, TNF-α, IL-1ß, and MIP-2 were suppressed by inhibiting NF-κB activation in the lung tissues of the AGE group. These effects are associated with scopolin, chlorogenic acid, hyperoside, 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 4,5-di-O-caffeoylquinic acid, which are the main components of AGE. These data demonstrate the mitigation effect of AGE on lung inflammation via inhibition of MAPK and NF-κB pathways, suggesting that AGE may be instrumental in improving respiratory and lung health.

Epilobiumpyrricholophum Extract Suppresses Porcine Pancreatic Elastase and Cigarette Smoke Extract-Induced Inflammatory response in a Chronic Obstructive Pulmonary Disease Model.

Chronic airway exposure to harmful substances, such as deleterious gases, cigarette smoke (CS), and particulate matter, triggers chronic obstructive pulmonary disease (COPD), characterized by impaired lung function and unbridled immune responses. Emerging epigenomic and genomic evidence suggests that excessive recruitment of alveolar macrophages and neutrophils contributes to COPD pathogenesis by producing various inflammatory mediators, such as reactive oxygen species (ROS), neutrophil elastase, interleukin (IL) 6, and IL8. Recent studies showed that Epilobium species attenuated ROS, myeloperoxidase, and inflammatory cytokine production in murine and human innate immune cells. Although the Epilobium genus exerts anti-inflammatory, antioxidant, and antimicrobial effects, the question of whether the Epilobium species regulate lung inflammation and innate immune response in COPD has not been investigated. In this study, Epilobium pyrricholophum extract (EPE) suppressed inflammatory cell recruitment and clinical symptoms in porcine pancreatic elastase and CS extract-induced COPD mice. In addition, EPE attenuated inflammatory gene expression by suppressing MAPKs and NFκB activity. Furthermore, UPLC-Q-TOF MS analyses revealed the anti-inflammatory effects of the identified phytochemical constituents of EPE. Collectively, our studies revealed that EPE represses the innate immune response and inflammatory gene expression in COPD pathogenesis in mice. These findings provide insights into new therapeutic approaches for treating COPD.

BHLHE40 promotes macrophage pro-inflammatory gene expression and functions.

Macrophages are the principal innate immune cells that populate all major organs and provide the first line of cellular defense against infections and/or injuries. The immediate and early-responding macrophages must mount a robust pro-inflammatory response to protect the host by eliminating deleterious agents. The effective pro-inflammatory macrophage response requires the activation of complex transcriptional programs that modulate the dynamic regulation of inflammatory and metabolic gene expression. Therefore, transcription factors that govern pro-inflammatory and metabolic gene expression play an essential role in shaping the macrophage inflammatory response. Herein, we identify the basic helix-loop-helix family member e40 (BHLHE40), as a critical transcription factor that promotes broad pro-inflammatory and glycolytic gene expression by elevating HIF1α levels in macrophages. Our in vivo studies revealed that myeloid-BHLHE40 deficiency significantly attenuates macrophage and neutrophil recruitment to the site of inflammation. Our integrated transcriptomics and gene set enrichment analysis (GSEA) studies show that BHLHE40 deficiency broadly curtails inflammatory signaling pathways, hypoxia response, and glycolytic gene expression in macrophages. Utilizing complementary gain- and loss-of-function studies, our analyses uncovered that BHLHE40 promotes LPS-induced HIF1α mRNA and protein expression in macrophages. More importantly, forced overexpression of oxygen stable form of HIF1α completely reversed attenuated pro-inflammatory and glycolytic gene expression in BHLHE40-deficient macrophages. Collectively, these results demonstrate that BHLHE40 promotes macrophage pro-inflammatory gene expression and functions by elevating HIF1α expression in macrophages.

Miquelianin Inhibits Allergic Responses in Mice by Suppressing CD4+ T Cell Proliferation.

Allergic diseases, including atopic dermatitis (AD), induce type 2 helper T (Th2) cell-dominant immune responses. Miquelianin (quercetin 3-O-glucuronide, MQL) is an active compound in Rosae multiflorae fructus extract with anti-allergic properties. Here, we investigate the anti-allergic effects of MQL in an ovalbumin (OVA)-induced Th2-dominant mouse model and the associated mechanisms. Oral MQL suppressed cytokine and IL-2 production and proliferation of Th2 cells and upregulated heme oxygenase-1 (HO-1) in splenocytes. Ex vivo MQL suppressed Th1- and Th2-related immune responses by inhibiting CD4+ T cell proliferation, and upregulated HO-1 in CD4+ T cells by activating C-Raf-ERK1/2-Nrf2 pathway via induction of reactive oxygen species generation. In a trimellitic anhydride-induced AD-like mouse model, both topical and oral MQL ameliorated AD symptoms by suppressing Th2 immune responses. Our results suggest that MQL is a potential therapeutic agent for CD4+ T cell-mediated diseases, including allergic diseases.

CITED2 inhibits STAT1-IRF1 signaling and atherogenesis.

Macrophages are the principal component of the innate immune system. They play very crucial and multifaceted roles in the pathogenesis of inflammatory vascular diseases. There is an increasing recognition that transcriptionally dynamic macrophages are the key players in the pathogenesis of inflammatory vascular diseases. In this context, the accumulation and aberrant activation of macrophages in the subendothelial layers govern atherosclerotic plaque development. Macrophage-mediated inflammation is an explicitly robust biological response that involves broad alterations in inflammatory gene expression. Thus, cell-intrinsic negative regulatory mechanisms must exist which can restrain inflammatory response in a spatiotemporal manner. In this study, we identified CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) as one such cell-intrinsic negative regulator of inflammation. Our in vivo studies show that myeloid-CITED2-deficient mice on the Apoe-/- background have larger atherosclerotic lesions on both control and high-fat/high-cholesterol diets. Our integrated transcriptomics and gene set enrichment analyses studies show that CITED2 deficiency elevates STAT1 and interferon regulatory factor 1 (IRF1) regulated pro-inflammatory gene expression in macrophages. At the molecular level, our studies identify that CITED2 deficiency elevates IFNγ-induced STAT1 transcriptional activity and STAT1 enrichment on IRF1 promoter in macrophages. More importantly, siRNA-mediated knockdown of IRF1 completely reversed elevated pro-inflammatory target gene expression in CITED2-deficient macrophages. Collectively, our study findings demonstrate that CITED2 restrains the STAT1-IRF1 signaling axis in macrophages and limits the development of atherosclerotic plaques.

Macrophage-Hypoxia-Inducible Factor-1α Signaling in Carotid Artery Stenosis.

Macrophages play crucial and diverse roles in the pathogenesis of inflammatory vascular diseases. Macrophages are the principal innate immune cells recruited to arterial walls to govern vascular homeostasis by modulating the proliferation of vascular smooth muscle cells, the reorganization of extracellular matrix components, the elimination of dead cells, and the restoration of normal blood flow. However, chronic sterile inflammation within the arterial walls draws inflammatory macrophages into intimal/neointimal regions that may contribute to disease pathogenesis. In this context, the accumulation and aberrant activation of macrophages in the neointimal regions govern the progression of inflammatory arterial wall diseases. Herein, we report that myeloid-hypoxia-inducible factor-1α (HIF1α) deficiency attenuates vascular smooth muscle cells and macrophage abundance in stenotic arteries and abrogates carotid neointima formation in vivo. The integrated transcriptomics, Gene Set Enrichment Analysis, metabolomics, and target gene evaluation showed that HIF1α represses oxidative phosphorylation, tricarboxylic acid cycle, fatty acid metabolism, and c-MYC signaling pathways while promoting inflammatory, glycolytic, hypoxia response gene expression in stenotic artery macrophages. At the molecular level, proinflammatory agents utilized STAT3 signaling pathways to elevate HIF1α expression in macrophages. Collectively, this study uncovers that macrophage-HIF1α deficiency restrains the pathogenesis of carotid artery stenosis by rewiring inflammatory and metabolic signaling pathways in macrophages.

CITED2 limits pathogenic inflammatory gene programs in myeloid cells.

Monocyte-derived macrophages are the major innate immune cells that provide the first line of cellular defense against infections or injuries. These recruited macrophages at the site of inflammation are exposed to a broad range of cytokines that categorically incite a robust pro-inflammatory response. However, macrophage pro-inflammatory activation must be under exquisite control to avert unbridled inflammation. Thus, endogenous mechanisms must exist that rigorously preserve macrophage quiescence and yet, allow nimble pro-inflammatory macrophage response with precise spatiotemporal control. Herein, we identify the CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) as a critical intrinsic negative regulator of inflammation, which broadly attenuates pro-inflammatory gene programs in macrophages. Our in vivo studies revealed that myeloid-CITED2 deficiency significantly heightened macrophages and neutrophils recruitment to the site of inflammation. Our integrated transcriptomics and gene set enrichment analysis (GSEA) studies uncovered that CITED2 deficiency broadly enhances NFκB targets, IFNγ/IFNα responses, and inflammatory response gene expression in macrophages. Using complementary gain- and loss-of-function studies, we observed that CITED2 overexpression attenuate and CITED2 deficiency elevate LPS-induced NFκB transcriptional activity and NFκB-p65 recruitment to target gene promoter in macrophages. More importantly, blockade of NFκB signaling completely reversed elevated pro-inflammatory gene expression in macrophages. Collectively, our findings show that CITED2 restrains NFκB activation and curtails broad pro-inflammatory gene programs in myeloid cells.

Kruppel-like factor 6 promotes macrophage inflammatory and hypoxia response.

Macrophages are the professional phagocytes that protect the host from infection or injury. Tissue microenvironment at the site of injury and inflammation is characterized by low oxygen concentration and poor supply of nutrients. The responding macrophages have to advance against oxygen and nutrient gradients to reach the site of inflammation to perform host protection, and tissue repair functions. Thus, evolution has fashioned macrophages to orchestrate a coordinated inflammatory and hypoxic gene program to mount an effective immune response. Here, we discovered that Kruppel-like factor 6 (KLF6) governs macrophage functions by promoting inflammatory and hypoxic response gene programming. Our in vivo studies revealed that myeloid-KLF6-deficient mice were highly resistant to endotoxin-induced systemic inflammatory response syndrome symptomatology and mortality. Using complementary gain- and loss-of-function studies, we observed that KLF6 overexpression elevate and KLF6 deficiency attenuate inducible HIF1α expression in macrophages. Our integrated transcriptomics and gene set enrichment analysis studies uncovered that KLF6 deficiency attenuates broad inflammatory and glycolytic gene expression in macrophages. More importantly, overexpression of oxygen stable HIF1α reversed attenuated proinflammatory and glycolytic gene expression in KLF6-deficient macrophages. Collectively, our studies uncovered that KLF6 govern inflammatory and hypoxic response by regulating HIF1α expression in macrophage.

Kruppel-like factor 6 and miR-223 signaling axis regulates macrophage-mediated inflammation.

Macrophage-mediated inflammation is an explicitly robust biologic response that plays a critical role in maintaining tissue homeostasis by eliminating deleterious agents. These tissue macrophages tailor appropriate responses to external cues by altering inflammatory gene expression. Therefore, transcription factors and regulators that modulate inflammatory gene expression play an essential role in shaping the macrophage inflammatory response. Here, we identify that Kruppel-like factor (KLF)6 promotes inflammation by restraining microRNA-223 (miR-223) expression in macrophages. We uncovered that pro- and anti-inflammatory agents oppositely regulate KLF6 and miR-223 expression in macrophages. Using complementary gain- and loss-of-function studies, we observed that overexpression of KLF6 attenuates and deficiency of KLF6 elevates miR-223 expression in macrophages. Furthermore, heightened miR-223 expression in KLF6-deficient macrophages significantly attenuates inducible proinflammatory gene expression. Concordantly, myeloid-Klf6 deficiency significantly curbs diet-induced adipose tissue inflammation, obesity, glucose intolerance, and insulin resistance. At the molecular level, KLF6 directly represses miR-223 expression by occupying its promoter region. More importantly, genetic inhibition of miR-223-3P in KLF6-deficient macrophages completely reversed attenuated proinflammatory gene expression in macrophages. Collectively, our studies reveal that KLF6 promotes proinflammatory gene expression and functions by repressing miR-223 expression in macrophages.-Kim, G.-D., Ng, H. P., Patel, N., Mahabeleshwar, G. H. Kruppel-like factor 6 and miR-223 signaling axis regulates macrophage-mediated inflammation.

CITED2 Restrains Proinflammatory Macrophage Activation and Response.

Macrophages are strategically distributed in mammalian tissues and play an essential role in priming the immune response. However, macrophages need to constantly strike a balance between activation and inhibition states to avoid a futile inflammatory reaction. Here, we identify the CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) as a potent repressor of macrophage proinflammatory activation. Gain- and loss-of-function studies revealed that CITED2 is required for optimal peroxisome proliferator-activated receptor gamma (PPARγ) activation and attendant select anti-inflammatory gene expression in macrophages. More importantly, deficiency of CITED2 resulted in significant attenuation of rosiglitazone-induced PPARγ activity, PPARγ recruitment to target gene promoters, and anti-inflammatory target gene expression in macrophages. Interestingly, deficiency of Cited2 strikingly heightened proinflammatory gene expression through stabilization of hypoxia-inducible factor 1 alpha (HIF1α) protein in macrophages. Further, overexpression of Egln3 or inhibition of HIF1α in Cited2-deficient macrophages completely reversed elevated proinflammatory cytokine/chemokine gene expression. Importantly, mice bearing a myeloid cell-specific deletion of Cited2 were highly susceptible to endotoxin-induced sepsis symptomatology and mortality. Collectively, our observations identify CITED2 as a novel negative regulator of macrophage proinflammatory activation that protects the host from inflammatory insults.

Kruppel-like Factor 6 Promotes Macrophage-mediated Inflammation by Suppressing B Cell Leukemia/Lymphoma 6 Expression.

Macrophages are the predominant innate immune cells recruited to tissues following injury or infection. These early-responding, pro-inflammatory macrophages play an essential role in the amplification of inflammation. However, macrophage pro-inflammatory gene expression should be tightly regulated to avert host tissue damage. In this study, we identify the Kruppel-like transcription factor 6 (KLF6)-B cell leukemia/lymphoma 6 (BCL6) signaling axis as a novel regulator of macrophage inflammatory gene expression and function. Utilizing complementary gain- and loss-of-function studies, we observed that KLF6 is essential for macrophage motility under ex vivo and in vivo conditions. Concordant with these observations, myeloid-specific deficiency of KLF6 significantly attenuates macrophage pro-inflammatory gene expression, recruitment, and progression of inflammation. At the molecular level, KLF6 suppresses BCL6 mRNA and protein expression by elevating PR domain-containing 1 with ZNF domain (PRDM1) levels in macrophages. Interestingly, pharmacological or genetic inhibition of BCL6 in KLF6-deficient macrophages completely abrogated the attenuation of pro-inflammatory cytokine/chemokine expression and cellular motility. Collectively, our observations reveal that KLF6 repress BCL6 to enhance macrophage inflammatory gene expression and function.

Aspartame Attenuates 2, 4-Dinitrofluorobenzene-Induced Atopic Dermatitis-Like Clinical Symptoms in NC/Nga Mice.

Atopic dermatitis (AD) is a common multifactorial chronic skin disease that has a multiple and complex pathogenesis. AD is gradually increasing in prevalence globally. In NC/Nga mice, repetitive applications of 2, 4-dinitrofluorobenzene (DNFB) evoke AD-like clinical symptoms similar to human AD. Aspartame (N-L-α-aspartyl-L-phenylalanine 1-methyl ester) is a methyl ester of a dipeptide, which is used as an artificial non-nutritive sweetener. Aspartame has analgesic and anti-inflammatory functions that are similar to the function of nonsteroidal anti-inflammatory drugs such as aspirin. We investigated whether aspartame can relieve AD-like clinical symptoms induced by DNFB treatment in NC/Nga mice. Sucrose did not relieve AD-like symptoms, whereas aspartame at doses of 0.5 µg kg(-1) and 0.5 mg kg(-1) inhibited ear swelling and relieved AD-like clinical symptoms. Aspartame inhibited infiltration of inflammatory cells including eosinophils, mast cells, and CD4(+) T cells, and suppressed the expression of cytokines including IL-4 and IFN-γ, and total serum IgE levels. Aspartame may have therapeutic value in the treatment of AD.

Effects of Eicosapentaenoic Acid on the Cytoprotection Through Nrf2-Mediated Heme Oxygenase-1 in Human Endothelial Cells.

Consumption of omega-3 polyunsaturated fatty acid, particularly eicosapentaenoic acid (EPA), is associated with a significant reduction in the risk of developing cardiovascular disease. The aim of this study was to investigate whether heme oxygenase-1 (HO-1) induction contributes to the cytoprotective effects of EPA in endothelial cells threatened with oxidative damage. In this study, we investigated the effect of EPA on the induction of HO-1 by NF-E2-related factor 2 (Nrf2) in human umbilical vein endothelial cells. In cells treated with low concentrations of EPA (10-25 µM), HO-1 expression increased in a time- and concentration-dependent manner. Additionally, EPA treatment increased Nrf2 nuclear translocation and antioxidant response element activity, leading to the upregulation of HO-1 expression. Furthermore, treatment with EPA reduced hydrogen peroxide (H(2)O(2))-induced cell death. The reduction in cell death was reversed by treatment with zinc protoporphyrin, an inhibitor of HO-1, indicating that HO-1 contributed to the protective effect of EPA. These data suggest that EPA protects against H(2)O(2)-induced oxidative stress in endothelial cells by activating Nrf2 and inducting HO-1 expression.