MEK1 dependent and independent ERK activation regulates IL-10 and IL-12 production in bone marrow derived macrophages

Lipopolysaccharide pretreatment increases the sensitivity of the TRPV1 channel and promotes an anti-inflammatory phenotype of capsaicin-activated macrophages

BACKGROUND

The transient receptor potential vanilloid 1 (TRPV1) is well-established in neuronal function, yet its role in immune reactions remains enigmatic. The conflicting data on its inflammatory role, suggesting both pro-inflammatory and anti-inflammatory effects upon TRPV1 stimulation in immune cells, adds complexity. To unravel TRPV1 immunomodulatory mechanisms, we investigated how the TRPV1 agonist capsaicin influences lipopolysaccharide (LPS)-induced pro-inflammatory macrophage phenotypes.

RESULTS

Changes in the surface molecules, cytokine production, and signaling cascades linked to the phenotype of M1 or M2 macrophages of the J774 macrophage cell line and bone marrow-derived macrophages, treated with capsaicin before or after the LPS-induced inflammatory reaction were determined. The functional capacity of macrophages was also assessed by infecting the stimulated macrophages with the intracellular parasite Leishmania mexicana.

CONCLUSION

Our findings reveal that TRPV1 activation yields distinct macrophage responses influenced by the inflammatory context. LPS pre-treatment followed by capsaicin activation prompted increased calcium influx, accompanied by a shift toward an anti-inflammatory M2b-like polarization state.

Azithromycin Augments Bacterial Uptake and Anti-Inflammatory Macrophage Polarization in Cystic Fibrosis

BACKGROUND

Azithromycin (AZM) is widely being used for treating patients with cystic fibrosis (pwCF) following clinical trials demonstrating improved lung function and fewer incidents of pulmonary exacerba-tions. While the precise mechanisms remain elusive, immunomodulatory actions are thought to be involved. We previously reported impaired phagocytosis and defective anti-inflammatory M2 macrophage polarization in CF. This study systematically analyzed the effect of AZM on the functions of unpolarized and M1/M2 polarized macrophages in CF.

METHODS

Monocytes, isolated from the venous blood of patients with CF (pwCF) and healthy controls (HCs), were differentiated into monocyte-derived macrophages (MDMs) and subsequently infected with P. aeruginosa. P. aeruginosa uptake and killing by MDMs in the presence or absence of AZM was studied. M1 and M2 macrophage polarizations were induced and their functions and cytokine release were analyzed.

RESULTS

Following AZM treatment, both HC and CF MDMs exhibited a significant increase in P. aeruginosa uptake and killing, however, lysosomal acidification remained unchanged. AZM treatment led to higher activation of ERK1/2 in both HC and CF MDMs. Pharmacological inhibition of ERK1/2 using U0126 significantly reduced P. aeruginosa uptake in HC MDMs. M1 macrophage polarization remained unaffected; however, AZM treatment led to increased IL-6 and IL-10 release in both HC and CF M1 macrophages. AZM also significantly increased the phagocytic index for both pHrodo E. coli and S. aureus in CF M1 macrophages. In CF, AZM treatment promoted anti-inflammatory M2 macrophage polarization, with an increased percentage of CD209+ M2 macrophages, induction of the M2 gene CCL18, along with its secretion in the culture supernatant. However, AZM d'd not restore endocytosis in CF, another essential feature of M2 macrophages.

CONCLUSIONS

This study highlights the cellular functions and molecular targets of AZM which may involve an improved uptake of both Gram-positive and Gram-negative bacteria, restored anti-inflammatory macrophage polarization in CF. This may in turn shape the reduced lung inflammation observed in clinical trials. In addition, we confirmed the role of ERK1/2 activation for bacterial uptake.

Prolonged warm ischemia time increases mitogen-activated protein kinase activity and decreases perfusate cytokine levels in ex vivo rat liver machine perfusion

Introduction

Machine perfusion is increasingly being utilized in liver transplantation in lieu of traditional cold static organ preservation. Nevertheless, better understanding of the molecular mechanisms underlying the ischemia-reperfusion injury (IRI) during ex vivo perfusion is necessary to improve the viability of liver grafts after transplantation using machine perfusion technology. Since key cellular signaling pathways involved in hepatic IRI may allow a chance for designing a promising approach to improve the clinical outcomes from this technology, we determined how warm ischemia time (WIT) during procurement affects the activity of mitogen-activated protein kinase (MAPK) and perfusate concentration of cytokines in an ex vivo rat liver machine perfusion model.

Methods

Male Sprague-Dawley rats underwent in situ hepatic ischemia with varying WIT (0, 10, 20, 30 min, n = 5 each), and subsequently 3 h of cold ischemia time and 2 h of machine perfusion prior to determining the degree of MAPK activation-phosphorylation and cytokine concentration in liver tissue and perfusates, respectively.

Results

Our data revealed a strong correlation between incremental WIT and a series of liver injury markers, and that prolonged WIT increases ERK1/2 and p54 JNK phosphorylation during machine perfusion. Notably, specific cytokine levels (MCP-1, MIP-2, GRO/KC, IL-10, and IL-5) were inversely correlated with the phosphorylation levels of ERK1/2, p38 MAPK, and p46/p54 JNK.

Discussion

These results suggest that MAPK activation, specifically ERK1/2 and p54 JNK phosphorylation, have potential as a biomarker for hepatic IRI pathophysiology during machine perfusion. Elucidation of their functional significance may lead to designing a novel strategy to increase the clinical benefit of machine perfusion.

The Role of Intracellular Signaling Molecules in Macrophage Activation by Peat Humic Acids

Humic acids isolated by sodium pyrophosphate extraction from various types of peat activate macrophages in the classical proinflammatory pathway and stimulate nitric oxide production by these cells. This effect is mediated by activation of intracellular signaling pathways involving MAPK p38, PI3K, MEK 1/2 kinase, cAMP, and NF-κB via TLR-2 and TLR-4 receptors.

The Synergistic Hepatoprotective Activity of Rosemary Essential Oil and Curcumin: The Role of the MEK/ERK Pathway

BACKGROUND

Curcumin is a natural product obtained from the rhizome of Curcuma longa. Rosemary (Rosmarinus officinalis) is a medicinal and aromatic plant that is widely spread in the Mediterranean region. Both Curcumin and rosemary essential oil are natural products of high medicinal and pharmacological significance. The hepatoprotective effect of both natural products is well-established; however, the mechanism of such action is not fully understood. Thus, this study is an attempt to explore the hepatoprotective mechanism of action of these remedies through their effect on MEK and ERK proteins. Furthermore, the effect of rosemary essential oil on the plasma concentration of curcumin has been scrutinized.

MATERIALS AND METHODS

The major constituents of REO were qualitatively and quantitatively determined by GC/MS and GC/FID, respectively. Curcumin and rosemary essential oil were given to mice in a pre-treatment model, followed by induction of liver injury through a high dose of paracetamol. Serum liver enzymes, lipid peroxidation, antioxidant activities, the inflammatory and apoptotic biomarkers, as well as the MEK and ERK portions, were verified. The plasma levels of curcumin were determined in the presence and absence of rosemary essential oil.

RESULTS

The major constituents of REO were 1,8-cineole (51.52%), camphor (10.52%), and α-pinene (8.41%). The results revealed a superior hepatoprotective activity of the combination when compared to each natural product alone, as demonstrated by the lowered liver enzymes, lipid peroxidation, mitigated inflammatory and apoptotic biomarkers, and enhanced antioxidant activities. Furthermore, the combination induced the overexpression of MEK and ERK proteins, providing evidence for the involvement of this cascade in the hepatoprotective activity of such natural products. The administration of rosemary essential oil with curcumin enhanced the curcuminoid plasma level.

CONCLUSION

The co-administration of both curcumin and rosemary essential oil together enhanced both their hepatoprotective activity and the level of curcumin in plasma, indicating a synergistic activity between both natural products.

Temporary Shutdown of ERK1/2 Phosphorylation Is Associated With Activation of Adaptive Immune Cell Responses and Disease Progression During Leishmania amazonensis Infection in BALB/c Mice

Leishmania spp. infection outcomes are dependent on both host and parasite factors. Manipulation of host signaling pathways involved in the generation of immune responses is thought to be one of the most common mechanisms used by parasites for persistence within the host. Considering the diversity of pathologies caused by different Leishmania spp., it is plausible that significant differences may exist in the mechanisms of host cell manipulation by each parasite species, which may have implications when developing new vaccine or treatment strategies. Here we show that in L. braziliensis-infection in BALB/c mice, a model of resistance, activation of ERK1/2 coincides with the peak of inflammatory responses and resolution of tissue parasitism. In contrast, in the susceptibility model of L. amazonensis-infection, an early silent phase of infection is observed, detected solely by quantification of parasite loads. At this early stage, only basal levels of P-ERK1/2 are observed. Later, after a brief shutdown of ERK1/2 phosphorylation, disease progression is observed and is associated with increased inflammation, lesion size and tissue parasitism. Moreover, the short-term down-regulation of ERK1/2 activation affected significantly downstream inflammatory pathways and adaptive T cell responses. Administration of U0126, a MEK/ERK inhibitor, confirmed this phenomenon, since bigger lesions and higher parasite loads were seen in infected mice that received U0126. To investigate how kinetics of ERK1/2 activation could affect the disease progression, U0126 was administered to L. amazonensis-infected animals earlier than the P-ERK1/2 switch off time-point. This intervention resulted in anticipation of the same effects on inflammatory responses and susceptibility phenotype seen in the natural course of infection. Additionally, in vitro inhibition of ERK1/2 affected the phagocytosis of L. amazonensis by BMDMs. Collectively, our findings reveal distinct temporal patterns of activation of inflammatory responses in L. braziliensis and L. amazonensis in the same animal background and a pivotal role for a brief and specific shutdown of ERK1/2 activation at late stages of L. amazonensis infection. Since activation of inflammatory responses is a crucial aspect for the control of infectious processes, these findings may be important for the search of new and specific strategies of vaccines and treatment for tegumentary leishmaniasis.

Knockdown of PAK1 Inhibits the Proliferation and Invasion of Non-Small Cell Lung Cancer Cells Through the ERK Pathway

The p21-activated kinase (PAK) family of serine/threonine kinases plays a pivotal role in various human tumors, as supported by our previous report on the overexpressed PAK isoforms in non-small cell lung cancer (NSCLC). To better understand the role of PAKs in tumorigenesis, the authors examined PAK1 expression patterns and its significance in NSCLC. It was demonstrated by immunohistochemical staining that PAK1 was increased and localized in the cytoplasm in 151 of 207 cases. High levels of PAK1 expression correlated with a histologic type of tumor (squamous cell carcinoma), tumor node metastasis stage, and lymph nodal status. We also examined the biological role of PAK1 in lung cancer cell lines transfected with PAK1-small interfering RNA. Decreased expression of PAK1 inhibited lung cancer cell proliferation and invasion, which is the major cause of lung cancer malignancy. Downregulated expression of PAK1 hampered rapidly accelerated fibrosarcoma/mitogen-activated extracellular signal-regulated kinase/extracellular signal-regulated kinase pathway activity but did not affect Wnt/β-catenin signaling. Our findings suggest that PAK1 is an important oncogene in NSCLC, as decreased expression of PAK1 inhibited the proliferation and invasion of NSCLC cells by blocking the ERK pathway. These results provide evidence for using PAK1 inhibition as potential anticancer therapy.

Trichinella spiralis cystatin, TsCstN, modulates STAT4/IL-12 to specifically suppress IFN-γ production

We have previously identified a cystatin, TsCstN, derived from the L1 stage of Trichinella spiralis and have shown that this protein is internalised in macrophages. Here we sought to address if this macrophage-TsCstN interaction could alter downstream T-cell priming. Using LPS-primed macrophages to stimulate T-cells in a co-culture system with or without TsCstN we assessed the resultant T-cell outcomes. IFN-γ, both protein and mRNA, but not IL-17A was negatively regulated by inclusion of TsCstN during macrophage priming. We identified a cell-cell contact independent change in the levels of IL-12 that led to altered phosphorylated STAT4 levels and translocation. TsCstN also negatively regulated the autonomous response in the myotubule cell line, C2C12. This work identifies a potential pathyway for L1 larvae to evade protective Th1 based immune responses and establish muscle-stage T. spiralis infection.

Increased Interleukin-10 Expression by the Inhibition of Ca2+-Activated K+ Channel KCa3.1 in CD4+CD25+ Regulatory T Cells in the Recovery Phase in an Inflammatory Bowel Disease Mouse Model

Inflammatory bowel diseases (IBD) are chronic inflammatory diseases of the gastrointestinal tract arising from abnormal responses of the innate and adaptative immune systems. Interleukin (IL)-10-producing CD4⁺CD25⁺ regulatory T (T_reg) cells play a protective role in the recovery phase of IBD. In the present study, the effects of the administration of the selective Ca²⁺-activated K⁺ channel K_Ca3.1 inhibitor TRAM-34 on disease activities were examined in chemically induced IBD model mice. IBD disease severity, as assessed by diarrhea, visible fecal blood, inflammation, and crypt damage in the colon, was significantly lower in mice administered 1 mg/kg TRAM-34 than in vehicle-administered mice. Quantitative real-time polymerase chain reaction examinations showed that IL-10 expression levels in the recovery phase were markedly increased by the inhibition of K_Ca3.1 in mesenteric lymph node (mLN) T_reg cells of IBD model mice compared with vehicle-administered mice. Among several positive and negative transcriptional regulators (TRs) for IL-10, three positive TRs-E4BP4, KLF4, and Blimp1-were upregulated by the inhibition of K_Ca3.1 in the mLN T_reg cells of IBD model mice. In mouse peripheral CD4⁺CD25⁺ T_reg cells induced by lectin stimulation, IL-10 expression and secretion were enhanced by the treatment with TRAM-34, together with the upregulation of E4BP4, KLF4, and Blimp1. Collectively, the present results demonstrated that the pharmacological inhibition of K_Ca3.1 decreased IBD symptoms in the IBD model by increasing IL-10 production in peripheral T_reg cells and that IL-10^high T_reg cells produced by the treatment with K_Ca3.1 inhibitor may contribute to efficient T_reg therapy for chronic inflammatory disorders, including IBD. SIGNIFICANCE STATEMENT: Pharmacological inhibition of Ca²⁺-activated K⁺ channel K_Ca3.1 increased IL-10 expression in peripheral T_reg cells, together with the upregulation of the transcriptional regulators of IL-10: Krüppel-like factor 4, E4 promoter-binding protein 4, and/or B lymphocyte-induced maturation protein 1. The manipulation of IL-10^high-producing T_reg cells by the pharmacological inhibition of K_Ca3.1 may be beneficial in the treatment of chronic inflammatory diseases such as inflammatory bowel disease.

Toll-Like Receptor 2-Tpl2-Dependent ERK Signaling Drives Inverse Interleukin 12 Regulation in Dendritic Cells and Macrophages

This study investigated responses to Toll-like receptor 2 (TLR2)-driven extracellular signal-related kinase (ERK) signaling in dendritic cells (DCs) versus macrophages. TLR2 signaling was induced with Pam₃Cys-Ser-Lys₄, and the role of ERK signaling was interrogated pharmacologically with MEK1/2 inhibitor U0126 or genetically with bone marrow-derived macrophages or DCs from Tpl2^-/- mice. We assessed cytokine production via enzyme-linked immunosorbent assay (ELISA) or V-Plex, and mRNA levels were assessed via reverse transcriptase quantitative PCR (qRT-PCR). In macrophages, blockade of ERK signaling by pharmacologic or genetic approaches inhibited interleukin 10 (IL-10) expression and increased expression of the p40 subunit shared by IL-12 and IL-23 (IL-12/23p40). In DCs, blockade of ERK signaling similarly inhibited IL-10 expression but decreased IL-12/23p40 expression, which is opposite to the effect of ERK signaling blockade on IL-12/23p40 in macrophages. This difference in IL-12/23p40 regulation correlated with the differential expression of transcription factors cFos and IRF1, which are known to regulate IL-12 family members, including IL-12 and IL-23. Thus, the impact of ERK signaling in response to TLR2 stimulation differs between macrophages and DCs, potentially regulating their distinctive functions in the immune system. ERK-mediated suppression of IL-12/23p40 in macrophages may prevent excessive inflammation and associated tissue damage following TLR2-stimulation, while ERK-mediated induction of IL-12/23p40 in DCs may promote priming of T helper 1 (Th1) responses. A greater understanding of the role that ERK signaling plays in different immune cell types may inform the development of host-directed therapy and optimal adjuvanticity for a number of infectious pathogens.

MEK2 Negatively Regulates Lipopolysaccharide-Mediated IL-1β Production through HIF-1α Expression

LPS-activated macrophages require metabolic reprogramming and glucose uptake mediated by hypoxia-inducible factor (HIF)-1 α and glucose transporter 1 (Glut1) expression for proinflammatory cytokine production, especially IL-1β. This process is tightly regulated through activation of MAPK kinases, including the MEK/ERK pathway as well as several transcription factors including HIF-1α. Although MAPK kinase (MEK) 2 deficiency had no significant effect on NO, TNF-α, or IL-12 production in response to LPS challenge, MEK2-deficient murine bone marrow-derived macrophages (BMDMs) exhibited lower IL-10 production. Importantly, MEK2-deficient BMDMs exhibited a preserved ERK1/2 phosphorylation, higher HIF-1α and Glut1 levels, and substantially increased IL-1β as well as IL-6 production in response to LPS stimulation. Knockdown of HIF-1α expression via short interference RNA decreased the level of HIF-1α expression in MEK2-deficient BMDMs and decreased IL-1β production in response to LPS treatment. Furthermore, we performed gain of function experiments by overexpressing MEK2 protein in RAW264.7 cells. LPS stimulation of MEK2 overexpressed in RAW264.7 cells led to a marked decreased IL-1β production. Finally, we investigated the role of Mek1 and Mek2 double and triple mutation on ERK phosphorylation, HIF-1α expression, and IL-1β production. We found that MEK2 is the major kinase, which inversely proportionally regulates HIF-1α and IL-1β expression independent of ERK activation. Our findings demonstrate a novel regulatory function for MEK2 in response to TLR4 activation in IL-1β production through modulating HIF-1α expression.

Interleukin-10 negatively modulates extracellular signal-regulated kinases 1 and 2 in aorta from hypertensive mouse induced by angiotensin II infusion

The activation of extracellular signal-regulated kinase 1 and 2 (ERK 1/2) pathway promotes increased vascular contractility in angiotensin II (Ang II)-induced hypertensive mice. Interleukin-10 (IL-10) is an immune-regulatory cytokine with the ability to prevent vascular hypercontractility during hypertension. We hypothesized that IL-10 would downregulate vascular ERK 1/2 activation during Ang II-induced hypertension. Wild-type (WT) or IL-10 knockout (IL-10-/- ) mice received Ang II infusion (90 ηg.min) or vehicle (saline), via osmotic mini-pumps (0.25 μL/h for 14 days), whereas another WT group were infused with exogenous IL-10 (0.5 ηg/min, 14 days) simultaneously, or not, with Ang II. Aortic rings were mounted in a myograph, and concentration-response curves to phenylephrine were evaluated, in the presence or absence of ERK 1/2 inhibitor (PD98059, 10 μm, 40 min). Protein expression of vascular ERK 1/2 was determined by Western blot. Ang II infusion increased the maximal contractile response in both WT and IL-10-/- mice. Concomitant infusion of IL-10 and Ang II prevented hypercontractility in the vasculature. Exogenous IL-10 infusion prevented ERK 1/2 activation and hypercontractility, induced by Ang II. These findings suggest that IL-10 negatively modulates ERK 1/2 activation and prevents hypercontractility during Ang II-induced hypertension.

Vemurafenib Limits Influenza A Virus Propagation by Targeting Multiple Signaling Pathways

Influenza A viruses (IAV) can cause severe global pandemic outbreaks. The currently licensed antiviral drugs are not very effective and prone to viral resistance. Thus, novel effective and broadly active drugs are urgently needed. We have identified the cellular Raf/MEK/ERK signaling cascade as crucial for IAV replication and suitable target for an antiviral intervention. Since this signaling cascade is aberrantly activated in many human cancers, several clinically approved inhibitors of Raf and MEK are now available. Here we explored the anti-IAV action of the licensed B-RafV600E inhibitor Vemurafenib. Treatment of B-RafWT cells with Vemurafenib induced a hyperactivation of the Raf/MEK/ERK cascade rather than inhibiting its activation upon IAV infection. Despite this hyperactivation, which has also been confirmed by others, Vemurafenib still strongly limited IAV-induced activation of other signaling cascades especially of p38 and JNK mitogen-activated protein kinase (MAPK) pathways. Most interestingly, Vemurafenib inhibited virus-induced apoptosis via impaired expression of apoptosis-inducing cytokines and led to hampered viral protein expression most likely due to the decreased activation of p38 and JNK MAPK. These multiple actions resulted in a profound and broadly active inhibition of viral replication, up to a titer reduction of three orders of a magnitude. Thus, while Vemurafenib did not act similar to MEK inhibitors, it displays strong antiviral properties via a distinct and multi-target mode of action.

Watsonianone A from Rhodomyrtus tomentosa Fruit Attenuates Respiratory-Syncytial-Virus-Induced Inflammation In Vitro

Respiratory syncytial virus (RSV) is one of the most common respiratory pathogens. Immoderate inflammation plays a great role in causing RSV-induced diseases. In the present study, watsonianone A, isolated from the fruit of Rhodomyrtus tomentosa (Ait.) Hassk, was found to show a good inhibitory effect on RSV-induced NO production, with a half-maximal inhibitory concentration of 37.2 ± 1.6 μM. Enzyme-linked immunosorbent assay and fluorescence quantitative polymerase chain reaction analyses indicated that watsonianone A markedly reduced both mRNA and protein levels of tumor necrosis factor α, interleukin 6, and monocyte chemoattractant protein 1 in RSV-infected RAW264.7 cells. Mechanistically, watsonianone A inhibited nuclear factor κB (NF-κB) activation by suppressing IκBα phosphorylation. Further analysis revealed that watsonianone A activated the thioredoxin system and decreased intracellular reactive oxygen species (ROS) levels, which are closely associated with NF-κB activation in RSV-infected cells. These results reveal that watsonianone A can attenuate RSV-induced inflammation via the suppression of ROS-sensitive inflammatory signaling.

Immunomodulatory effect of protease hydrolysates from ovotransferrin

Proteins and bioactive peptides in avian egg white exert diverse biological activities. This study is designed to investigate the effect of protease hydrolysates from ovotransferrin (OVT) on bone marrow-derived dendritic cells (BMDCs) maturation. The results show that OVT-derived pepsin hydrolysate effectively inhibits lipopolysaccharide (LPS)-induced BMDCs maturation by reducing the expression levels of MHC-II, CD83, CD86 and the production of TNF-α, IL-12p70, and RANTES, but increases the production of IL-10. In addition, OVT-derived pepsin hydrolysate impairs the ability of LPS-stimulated BMDCs to induce allogeneic T lymphocyte proliferation and decreases the production of IFN-γ by activated T cells. In contrast, OVT-derived trypsin hydrolysate induces DCs maturation in terms of increasing the expression levels of MHC-II and the costimulatory molecules CD83 and CD86 and the production of TNF-α, IL-12p70 and RANTES. Furthermore, OVT-derived trypsin hydrolysate improves the ability of LPS-stimulated DCs to induce allogeneic T lymphocyte activation. Blockage of LPS-induced p38 MAPK and JNK activation and inducing ERK activation contribute to the inhibitory effect of OVT-derived pepsin hydrolysate on DCs, whereas OVT-derived trypsin hydrolysate induces DCs maturation through JNK and ERK activation. These results indicate that OVT-derived protease hydrolysate have an immunomodulatory function and could be applied as a potential functional food ingredient to regulate body immunity by modulating DC maturation.

A Helminth Protease Inhibitor Modulates the Lipopolysaccharide-Induced Proinflammatory Phenotype of Microglia in vitro

OBJECTIVE

The aim of this study was to examine whether the natural protease inhibitor Av-cystatin (rAv17) of the parasitic nematode Acanthocheilonema viteae exerts anti-inflammatory effects in an in vitro model of lipopolysaccharide (LPS)-activated microglia.

METHODS

Primary microglia were harvested from the brains of 2-day-old Wistar rats and cultured with or without rAv17 (250 nM). After 6 and 24 h the release of nitric oxide (Griess reagent) and TNF-α (ELISA) was measured in the supernatant. Real-time PCR was performed after 2, 6 and 24 h of culture to measure the mRNA expression of IL-1β, IL-6, TNF-α, COX-2, iNOS and IL-10. To address the involved signaling pathways, nuclear NF-x0138;B translocation was visualized by immunocytochemistry. Morphological changes of microglia were analyzed by Coomassie blue staining. Differences between groups were calculated using one-way ANOVA with Bonferroni's post hoc test.

RESULTS

Morphological analysis indicated that LPS-induced microglial transformation towards an amoeboid morphology is inhibited by rAv17. Av-cystatin caused a time-dependent downregulation of proinflammatory cytokines, iNOS and COX-2 mRNA expression, respectively. This was paralleled by an upregulated expression of IL-10 in resting as well as in LPS-stimulated microglia. Av-cystatin reduced the release of NO and TNF-α in the culture supernatant. Immunocytochemical staining demonstrated an attenuated translocation of NF-x0138;B by Av-cystatin in response to LPS. In addition, Western blot analysis revealed a rAv17-dependent reduction of the LPS-induced ERK1/2-pathway activation.

CONCLUSION

The parasite-derived secretion product Av-cystatin inhibits proinflammatory mechanisms of LPS-induced microglia with IL-10, a potential key mediator.