Lipopolysaccharide and proinflammatory cytokines stimulate interleukin-6 expression in C2C12 myoblasts: role of the Jun NH2-terminal kinase

IL-6 is a major inflammatory cytokine that plays a central role in coordinating the acute-phase response to trauma, injury, and infection in vivo. Although IL-6 is synthesized predominantly by macrophages and lymphocytes, skeletal muscle is a newly recognized source of this cytokine. IL-6 from muscle spills into the circulation, and blood-borne IL-6 can be elevated >100-fold due to exercise and injury. The purpose of the present study was to determine whether inflammatory stimuli, such as LPS, TNF-alpha, and IL-1beta, could increase IL-6 expression in skeletal muscle and C2C12 myoblasts. Second, we investigated the role of mitogen-activated protein (MAP) kinases, and the Jun NH2-terminal kinase (JNK) in particular, as a mediator of this response. Intraperitoneal injection of LPS in mice increased the circulating concentration of IL-6 from undetectable levels to 4 ng/ml. LPS also increased IL-6 mRNA 100-fold in mouse fast-twitch skeletal muscle. Addition of LPS, IL-1beta, or TNF-alpha directly to C2C12 myoblasts increased IL-6 protein (6- to 8-fold) and IL-6 mRNA (5- to 10-fold). The response to all three stimuli was completely blocked by the JNK inhibitor SP-600125 but not as effectively by other MAP kinase inhibitors. SP-600125 blocked LPS-stimulated IL-6 synthesis dose dependently at both the RNA and protein level. SP-600125 was as effective as the synthetic glucocorticoid dexamethasone at inhibiting IL-6 expression. SP-600125 inhibited IL-6 synthesis when added to cells up to 60 min after LPS stimulation, but its inhibitory effect waned with time. LPS stimulated IL-6 mRNA in both myoblasts and myotubes, but myoblasts showed a proportionally greater LPS-induced increase in IL-6 protein expression compared with myotubes. SP-600125 and the proteasomal inhibitor MG-132 blocked LPS-induced degradation of IkappaB-alpha/epsilon and LPS-stimulated expression of IkappaB-alpha mRNA. Yet, only SP-600125 and not MG-132 blocked LPS-induced IL-6 mRNA expression. This suggests that IL-6 gene expression is a downstream target of JNK in C2C12 myoblasts.     

Endogenous brain IL-1 mediates LPS-induced anorexia and hypothalamic cytokine expression

The present study was designed to determine the role of endogenous brain interleukin (IL)-1 in the anorexic response to lipopolysaccharide (LPS). Intraperitoneal administration of LPS (5-10 microgram/mouse) induced a dramatic, but transient, decrease in food intake, associated with an enhanced expression of proinflammatory cytokine mRNA (IL-1beta, IL-6, and tumor necrosis factor-alpha) in the hypothalamus. This dose of LPS also increased plasma levels of IL-1beta. Intracerebroventricular pretreatment with IL-1 receptor antagonist (4 microgram/mouse) attenuated LPS-induced depression of food intake and totally blocked the LPS-induced enhanced expression of proinflammatory cytokine mRNA measured in the hypothalamus 1 h after treatment. In contrast, LPS-induced increases in plasma levels of IL-1beta were not altered. These findings indicate that endogenous brain IL-1 plays a pivotal role in the development of the hypothalamic cytokine response to a systemic inflammatory stimulus.     

Honokiol inhibits LPS-induced maturation and inflammatory response of human monocyte-derived dendritic cells

Honokiol (HNK) is a phenolic compound isolated from the bark of houpu (Magnolia officinalis), a plant widely used in traditional Chinese and Japanese medicine. While substantial evidence indicates that HNK possesses anti-inflammatory activity, its effect on dendritic cells (DCs) during the inflammatory reaction remains unclear. The present study investigates how HNK affects lipopolysaccharide (LPS)-stimulated human monocyte-derived DCs. Our experimental results show that HNK inhibits the inflammatory response of LPS-induced DCs by (1) suppressing the expression of CD11c, CD40, CD80, CD83, CD86, and MHC-II on LPS-activated DCs, (2) reducing the production of TNF-α, IL-1β, IL-6, and IL-12p70 but increasing the production of IL-10 and TGF-β1 by LPS-activated DCs, (3) inhibiting the LPS-induced DC-elicited allogeneic T-cell proliferation, and (4) shifting the LPS-induced DC-driven Th1 response toward a Th2 response. Further, our results show that HNK inhibits the phosphorylation levels of ERK1/2, p38, JNK1/2, IKKα, and IκBα in LPS-activated DCs. Collectively, the findings show that the anti-inflammatory actions of HNK on LPS-induced DCs are associated with the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways.     

长链非编码RNA KCNQ1OT1影响脂多糖诱导的血管内皮细胞凋亡及其炎性因子表达的机制

该研究探讨了长链非编码RNA KCNQ1OT1对脂多糖(LPS)诱导的血管内皮细胞(VEC)凋亡和炎性因子表达的影响以及其可能机制.通过体外培养VEC,分别转染KCNQ1OT1过表达载体、miR-223抑制剂或共转染KCNQ1OT1过表达载体与miR-223模拟物后,用1.0mg/mLLPS干预24h,然后采用RT-q...     

Acanthopanax senticosus total flavonoids alleviate lipopolysaccharide-induced intestinal inflammation and modulate the gut microbiota in mice

Here, we study the therapeutic effect of Acanthopanax senticosus total flavonoids (ASTFs) using a mouse intestinal inflammation model. The inflammation model used in the present study was developed through lipopolysaccharide (LPS) treatment of mice. The experimental mice were divided into a control group, model group (10 mg/kg LPS), dexamethasone group (1 mg/kg DEX) and ASTF low-, medium- and high-dosage groups (200, 400 and 800 mg/kg, respectively). The morphological and structural changes in the ileum, jejunum and duodenum were observed using HE staining. The number of intestinal goblet cells (GCs) was calculated based on PAS staining. The contents of interleukin (IL)-1β, IL-6, prostaglandin E2 (PGE2) and tumor necrosis factor α (TNF-α) were determined using enzyme-linked immunosorbent assay (ELISA) and the related mRNA expression level were measured by RT-PCR. The protein expression levels of Toll-like receptor 4 (TLR4), MyD88, p65 and p-p65 were measured using Western blotting. In addition, the 16S rRNA sequences of bacterial taxa were amplified and analyzed to assess changes in the intestinal microbes of LPS-induced mice and also in response to regulation by ASTF. Following intervention with ASTF, different therapeutic effects were shown according to the various dosages tested, all of which resulted in improved intestinal morphology and an increased number of intestinal GCs, while the contents of IL-1β, IL-6, PGE2 and TNF-α and the related mRNA expression level were significantly reduced. The TLR4, MyD88 and p-p65/p-65 protein expression levels were also significantly reduced. In addition, 16S rRNA sequencing results show that LPS disrupts the structure of mouse gut microbes, though we observed that normal microbial status can be restored through ASTF intervention.     

Upregulation of lipopolysaccharide-induced interleukin-10 by prostaglandin A1 in mouse peritoneal macrophages

The cyclopentenone prostaglandins (cyPGs) prostaglandin A1 (PGA1) and 15-deoxy-12,14-prostaglandin J2 (15d-PGJ2) have been reported to exhibit antiinflammatory activity in activated monocytes/macrophages. However, the effects of these two cyPGs on the expression of cytokine genes may differ. In this study, we investigated the mechanism of action of PGA1 in lipopolysaccharide (LPS)-induced expression of interleukin (IL)-10 mRNA in mouse peritoneal macrophages. 15d-PGJ2 inhibited expression of LPSinduced IL-10, whereas PGA1 increased LPS-induced IL-10 expression. This synergistic effect of PGA1 on LPS-induced IL-10 expression reached a maximum as early as 2 h after simultaneous PGA1 and LPS treatment (PGA1/LPS), and did not require new protein synthesis. The synergistic effect of PGA1 was inhibited by GW9662, a specific peroxisome proliferator-activated receptor (PPAR) antagonist, and Bay-11-7082, a NF-kappaB inhibitor. The extracellular signalregulated kinases (ERK) inhibitor PD98059 increased the expression of PGA1/LPS-induced IL-10 mRNA, rather than inhibiting the IL-10 expression. Moreover, PGA1 inhibited LPS-induced ERK phosphorylation. The synergistic effect of PGA1 on LPS-induced IL-10 mRNA and protein production was inhibited by p38 inhibitor PD169316, and PGA1 increased LPS-induced p38 phosphorylation. In the case of stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK), the SAPK/JNK inhibitor SP600125 did not inhibit IL-10 mRNA synthesis but inhibited the production of IL-10 protein remarkably. These results suggest that the synergistic effect of PGA1 on LPS-induced IL-10 expression is NF-kappaB-dependent and mediated by mitogen-activated protein (MAP) kinases, p38, and SAPK/ JNK signaling pathways, and also associated with the PPARgamma pathway. Our data may provide more insight into the diverse mechanisms of PGA1 effects on the expression of cytokine genes.     

Activation of c-Jun-N-terminal kinase is critical in mediating lipopolysaccharide-induced changes in the rat hippocampus

Lipopolysaccharide (LPS) exerts a myriad of effects in rat hippocampus; it increases the concentration of the proinflammatory cytokine, interleukin-1beta (IL-1beta), and signalling via the IL-1 type I receptor (IL-1RI) resulting in phosphorylation of the stress-activated protein kinase, c-jun-N-terminal kinase (JNK) and impairment in long-term potentiation (LTP). This study was designed to establish whether activation of JNK is a pivotal event in mediating the effects of LPS in hippocampus and therefore LPS-treated rats were injected intracerebroventricularly with saline, the JNK inhibitor D-JNKI1, or with the anti-inflammatory cytokine IL-4, which antagonizes the effects of IL-1beta upstream of JNK activation. We report that IL-4 blocked the LPS-induced increase in IL-1RI expression and associated increases in phosphorylation of JNK and c-jun, whereas D-JNKI1 inhibited the LPS-induced phosphorylation of c-jun. Both IL-4 and D-JNKI1 inhibited the increase in caspase-3 staining which was associated with LPS treatment, and both abrogated the LPS-induced inhibition of LTP in perforant path-granule cell synapses. The data presented are consistent with the proposal that JNK activation, probably as a result of increased IL-1RI activation, is a critical step in mediating the detrimental effects of LPS in hippocampus.     

c-Jun N-terminal kinase negatively regulates lipopolysaccharide-induced IL-12 production in human macrophages: role of mitogen-activated protein kinase in glutathione redox regulation of IL-12 production

Although c-Jun N-terminal kinase (JNK) plays an important role in cytokine expression, its function in IL-12 production is obscure. The present study uses human macrophages to examine whether the JNK pathway is required for LPS-induced IL-12 production and defines how JNK is involved in the regulation of IL-12 production by glutathione redox, which is the balance between intracellular reduced (GSH) and oxidized glutathione (GSSG). We found that LPS induced IL-12 p40 protein and mRNA in a time- and concentration-dependent manner in PMA-treated THP-1 macrophages, and that LPS activated JNK and p38 mitogen-activated protein (MAP) kinase, but not extracellular signal-regulated kinase, in PMA-treated THP-1 cells. Inhibition of p38 MAP kinase activation using SB203580 dose dependently repressed LPS-induced IL-12 p40 production, as described. Conversely, inhibition of JNK activation using SP600125 dose dependently enhanced both LPS-induced IL-12 p40 production from THP-1 cells and p70 production from human monocytes. Furthermore, JNK antisense oligonucleotides attenuated cellular levels of JNK protein and LPS-induced JNK activation, but augmented IL-12 p40 protein production and mRNA expression. Finally, the increase in the ratio of GSH/GSSG induced by glutathione reduced form ethyl ester (GSH-OEt) dose dependently enhanced LPS-induced IL-12 p40 production in PMA-treated THP-1 cells. GSH-OEt augmented p38 MAP kinase activation, but suppressed the JNK activation induced by LPS. Our findings indicate that JNK negatively affects LPS-induced IL-12 production from human macrophages, and that glutathione redox regulates LPS-induced IL-12 production through the opposite control of JNK and p38 MAP kinase activation.     

Suppression of osteoprotegerin expression by prostaglandin E2 is crucially involved in lipopolysaccharide-induced osteoclast formation

LPS is a potent stimulator of bone resorption in inflammatory diseases. The mechanism by which LPS induces osteoclastogenesis was studied in cocultures of mouse osteoblasts and bone marrow cells. LPS stimulated osteoclast formation and PGE(2) production in cocultures of mouse osteoblasts and bone marrow cells, and the stimulation was completely inhibited by NS398, a cyclooxygenase-2 inhibitor. Osteoblasts, but not bone marrow cells, produced PGE(2) in response to LPS. LPS-induced osteoclast formation was also inhibited by osteoprotegerin (OPG), a decoy receptor of receptor activator of NF-kappaB ligand (RANKL), but not by anti-mouse TNFR1 Ab or IL-1 receptor antagonist. LPS induced both stimulation of RANKL mRNA expression and inhibition of OPG mRNA expression in osteoblasts. NS398 blocked LPS-induced down-regulation of OPG mRNA expression, but not LPS-induced up-regulation of RANKL mRNA expression, suggesting that down-regulation of OPG expression by PGE(2) is involved in LPS-induced osteoclast formation in the cocultures. NS398 failed to inhibit LPS-induced osteoclastogenesis in cocultures containing OPG knockout mouse-derived osteoblasts. IL-1 also stimulated PGE(2) production in osteoblasts and osteoclast formation in the cocultures, and the stimulation was inhibited by NS398. As seen with LPS, NS398 failed to inhibit IL-1-induced osteoclast formation in cocultures with OPG-deficient osteoblasts. These results suggest that IL-1 as well as LPS stimulates osteoclastogenesis through two parallel events: direct enhancement of RANKL expression and suppression of OPG expression, which is mediated by PGE(2) production.     

A novel chromone derivative with anti-inflammatory property via inhibition of ROS-dependent activation of TRAF6-ASK1-p38 pathway

The p38 MAPK signaling pathway plays a pivotal role in inflammation. Targeting p38 MAPK may be a potential strategy for the treatment of inflammatory diseases. In the present study, we show that a novel chromone derivative, DCO-6, significantly reduced lipopolysaccharide (LPS)-induced production of nitric oxide, IL-1β and IL-6, decreased the levels of iNOS, IL-1β and IL-6 mRNA expression in both RAW264.7 cells and mouse primary peritoneal macrophages, and inhibited LPS-induced activation of p38 MAPK but not of JNK, ERK. Moreover, DCO-6 specifically inhibited TLR4-dependent p38 activation without directly inhibiting its kinase activity. LPS-induced production of intracellular reactive oxygen species (ROS) was remarkably impaired by DCO-6, which disrupted the formation of the TRAF6-ASK1 complex. Administering DCO-6 significantly protected mice from LPS-induced septic shock in parallel with the inhibition of p38 activation and ROS production. Our results indicate that DCO-6 showed anti-inflammatory properties through inhibition of ROS-dependent activation of TRAF6-ASK1-p38 pathway. Blockade of the upstream events required for p38 MAPK action by DCO-6 may provide a new therapeutic option in the treatment of inflammatory diseases.     

Lipopolysaccharide-induced c-Jun NH2-terminal kinase activation in human neutrophils: role of phosphatidylinositol 3-Kinase and Syk-mediated pathways

Polymorphonuclear leukocytes (neutrophils) respond to lipopolysaccharide (LPS) through the up-regulation of several pro-inflammatory mediators. We have recently shown that LPS-stimulated neutrophils express monocyte chemoattractant protein 1 (MCP-1), an AP-1-dependent gene, suggesting that LPS activates the c-Jun N-terminal kinase (JNK) pathway in neutrophils. Previously, we have shown the activation of p38 MAPK, but not JNK, in suspended neutrophils stimulated with LPS but have recently shown activation of JNK by TNF-alpha in an adherent neutrophil system. We show here that exposure to LPS activates JNK in non-suspended neutrophils and that LPS-induced MCP-1 expression, but not tumor necrosis factor-alpha (TNF-alpha) or interleukin-8 (IL-8), is dependent on JNK activation. In addition, LPS stimulation of non-suspended neutrophils activates Syk and phosphatidylinositol 3-kinase (PI3K). Inhibition of Syk with piceatannol or PI3K with wortmannin inhibited LPS-induced JNK activation and decreased MCP-1 expression after exposure to LPS, suggesting that both Syk and PI3K reside in a signaling pathway leading to LPS-induced JNK activation in neutrophils. This Syk- and PI3K-dependent pathway leading to JNK activation after LPS exposure in non-suspended neutrophils is specific for JNK, because inhibition of neither Syk nor PI3K decreased p38 activation after LPS stimulation. Furthermore we show that PI3K inhibition decreased LPS-induced Syk activation suggesting that PI3K resides upstream of Syk in this pathway. Finally, we show that Syk associates with Toll-like receptor 4 (TLR4) upon LPS stimulation further implicating Syk in the LPS-induced signaling pathway in neutrophils. Overall our data suggests that LPS induces JNK activation only in non-suspended neutrophils, which proceeds through Syk- and PI3K-dependent pathways, and that JNK activation is important for LPS-induced MCP-1 expression but not for TNF-alpha or IL-8 expression.     

壳寡糖抑制脂多糖诱导的PIECs表达IL-8和VCAM-1作用的初步研究

目的：观察壳寡糖对脂多糖（LPS）诱导的猪髋动脉内皮细胞（PIECs）炎症损伤的影响以及潜在的分子机制。方法：以脂多糖（1g／mE）＊《激PIECs细胞,建立炎症损伤模型,以RT—PCR和Westernblot的方法观察壳寡糖（COS）预保护PIECs细胞24h,对白介素－8（IL－8）和血管细胞粘附分子．1（VCAM－1）表达水平的影响,以及对JNK信号蛋白磷酸化和c-Fos转录因子表达的影响。结果：壳寡糖可抑制脂多糖刺激的PIECs表达IL－8和VCAM－1,并抑制JNK信号通路的磷酸化和转录因子c-Fos的表达。结论：壳寡糖对脂多糖刺激的PIECs细胞中IL－8和VCAM—1表达的抑制作用是通过抑制上游的JNK信号通路磷酸化和转录因子c-Fos的表达实现的,从而缓解脂多糖对细胞造成的炎症损伤。     

Interleukin-35 Inhibits Endothelial Cell Activation by Suppressing MAPK-AP-1 Pathway

Vascular response is an essential pathological mechanism underlying various inflammatory diseases. This study determines whether IL-35, a novel responsive anti-inflammatory cytokine, inhibits vascular response in acute inflammation. Using a mouse model of LPS-induced acute inflammation and plasma samples from sepsis patients, we found that IL-35 was induced in the plasma of mice after LPS injection as well as in the plasma of sepsis patients. In addition, IL-35 decreased LPS-induced proinflammatory cytokines and chemokines in the plasma of mice. Furthermore, IL-35 inhibited leukocyte adhesion to the endothelium in the vessels of lung and cremaster muscle and decreased the numbers of inflammatory cells in bronchoalveolar lavage fluid. Mechanistically, IL-35 inhibited the LPS-induced up-regulation of endothelial cell (EC) adhesion molecule VCAM-1 through IL-35 receptors gp130 and IL-12Rβ2 via inhibition of the MAPK-activator protein-1 (AP-1) signaling pathway. We also found that IL-27, which shares the EBI3 subunit with IL-35, promoted LPS-induced VCAM-1 in human aortic ECs and that EBI3-deficient mice had similar vascular response to LPS when compared with that of WT mice. These results demonstrated for the first time that inflammation-induced IL-35 inhibits LPS-induced EC activation by suppressing MAPK-AP1-mediated VCAM-1 expression and attenuates LPS-induced secretion of proinflammatory cytokines/chemokines. Our results provide insight into the control of vascular inflammation by IL-35 and suggest that IL-35 is an attractive novel therapeutic reagent for sepsis and cardiovascular diseases.     

Biliverdin administration protects against endotoxin-induced acute lung injury in rats

Given the high morbidity and mortality rates associated with pulmonary inflammation in sepsis, there is a pressing need for new therapeutic modalities to prevent acute respiratory distress. The enzyme heme oxygenase-1 (HO-1) provides potent cytoprotection against lung injury; however, the mechanism by which it does so is unclear. HO-1 catabolizes heme into biliverdin (BV), which is rapidly converted to bilirubin by BV reductase. We tested the hypothesis that BV administration could substitute for the effects observed with HO-1. Using the well-described rat model of LPS-induced shock, we demonstrate that exposure to BV imparts a potent defense against lethal endotoxemia systemically, as well as in the lungs, and effectively abrogates the inflammatory response. BV administration before a lethal dose of LPS leads to a significant improvement in long-term survival: 87% vs. 20% in sham-treated controls. BV treatment suppressed LPS-induced increases in lung permeability and lung alveolitis and significantly reduced serum levels of the LPS-induced proinflammatory cytokine IL-6. Moreover, bilirubin administered just after LPS also abrogated lung inflammation. BV treatment also augmented expression of the anti-inflammatory cytokine IL-10. Similar effects on production were observed with BV treatment in vitro in mouse lung endothelial cells and RAW 264.7 macrophages treated with LPS. In conclusion, these data demonstrate that BV can modulate the inflammatory response and suppress pathophysiological changes in the lung and may therefore have therapeutic application in inflammatory disease states of the lung.     

TNFα and IL-1β are mediated by both TLR4 and Nod1 pathways in the cultured HAPI cells stimulated by LPS

A growing body of evidence recently suggests that glial cell activation plays an important role in several neurodegenerative diseases and neuropathic pain. Microglia in the central nervous system express toll-like receptor 4 (TLR4) that is traditionally accepted as the primary receptor of lipopolysaccharide (LPS). LPS activates TLR4 signaling pathways to induce the production of proinflammatory molecules. In the present studies, we verified the LPS signaling pathways using cultured highly aggressively proliferating immortalized (HAPI) microglial cells. We found that HAPI cells treated with LPS upregulated the expression of TLR4, phospho-JNK (pJNK) and phospho-NF-κB (pNF-κB), TNFα and IL-1β. Silencing TLR4 with siRNA reduced the expression of pJNK, TNFα and IL-1β, but not pNF-κB in the cells. Inhibition of JNK with SP600125 (a JNK inhibitor) decreased the expression of TNFα and IL-1β. Unexpectedly, we found that inhibition of Nod1 with ML130 significantly reduced the expression of pNF-κB. Inhibition of NF-κB also reduced the expression of TNFα and IL-1β. Nod1 ligand, DAP induced the upregulation of pNF-κB which was blocked by Nod1 inhibitor. These data indicate that LPS-induced pJNK is TLR4-dependent, and that pNF-κB is Nod1-dependent in HAPI cells treated with LPS. Either TLR4-JNK or Nod1-NF-κB pathways is involved in the expression of TNFα and IL-1β.     

Distinct role of p38 and c-Jun N-terminal kinases in IL-10-dependent and IL-10-independent regulation of the costimulatory molecule B7.2 in lipopolysaccharide-stimulated human monocytic cells

The costimulatory molecule B7.2 (CD86) plays a vital role in immune activation and development of Th responses. The molecular mechanisms by which B7.2 expression is regulated are not understood. We investigated the role of mitogen-activated protein kinases (MAPK) in the regulation of B7.2 expression in LPS-stimulated human monocytic cells. LPS stimulation of human monocytes resulted in the down-regulation of B7.2 expression that could be abrogated by anti-IL-10 Abs. Furthermore, SB202190, a specific inhibitor of p38 MAPK, inhibited LPS-induced IL-10 production and reversed B7.2 down-regulation, suggesting that LPS-induced B7.2 down-regulation may be mediated, at least in part, via regulation of IL-10 production by p38 MAPK. In contrast to human promonocytic THP-1 cells that are refractory to the inhibitory effects of IL-10, LPS stimulation enhanced B7.2 expression. This IL-10-independent B7.2 induction was not influenced by specific inhibitors of either p38 or p42/44 MAPK. To ascertain the role of the c-Jun N-terminal kinase (JNK) MAPK, dexamethasone, an inhibitor of JNK activation, was used, which inhibited LPS-induced B7.2 expression. Transfection of THP-1 cells with a plasmid expressing a dominant-negative stress-activated protein/extracellular signal-regulated kinase kinase 1 significantly reduced LPS-induced B7.2 expression, thus confirming the involvement of JNK. To study the signaling events downstream of JNK activation, we show that dexamethasone did not inhibit LPS-induced NF-kappaB activation in THP-1 cells, suggesting that JNK may not be involved in NF-kappaB activation leading to B7.2 expression. Taken together, our results reveal the distinct involvement of p38 in IL-10-dependent, and JNK in IL-10-independent regulation of B7.2 expression in LPS-stimulated monocytic cells.     

The effect of anti-inflammatory properties of ferritin light chain on lipopolysaccharide-induced inflammatory response in murine macrophages

Ferritin light chain (FTL) reduces the free iron concentration by forming ferritin complexes with ferritin heavy chain (FTH). Thus, FTL competes with the Fenton reaction by acting as an antioxidant. In the present study, we determined that FTL influences the lipopolysaccharide (LPS)-induced inflammatory response. FTL protein expression was regulated by LPS stimulation in RAW264.7 cells. To investigate the role of FTL in LPS-activated murine macrophages, we established stable FTL-expressing cells and used shRNA to silence FTL expression in RAW264.7 cells. Overexpression of FTL significantly decreased the LPS-induced production of tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), nitric oxide (NO) and prostaglandin E2 (PGE2). Additionally, overexpression of FTL decreased the LPS-induced increase of the intracellular labile iron pool (LIP) and reactive oxygen species (ROS). Moreover, FTL overexpression suppressed the LPS-induced activation of MAPKs and nuclear factor-κB (NF-κB). In contrast, knockdown of FTL by shRNA showed the reverse effects. Therefore, our results indicate that FTL plays an anti-inflammatory role in response to LPS in murine macrophages and may have therapeutic potential for treating inflammatory diseases.