IL-27 affects helper T cell responses via regulation of PGE2 production by macrophages.

IL-27 is a heterodimeric cytokine that regulates both innate and adaptive immunity. The immunosuppressive effect of IL-27 largely depends on induction of IL-10-producing Tr1 cells. To date, however, effects of IL-27 on regulation of immune responses via mediators other than cytokines remain poorly understood. To address this issue, we examined immunoregulatory effects of conditional medium of bone marrow-derived macrophages (BMDMs) from WSX-1 (IL-27Rα)-deficient mice and found enhanced IFN-γ and IL-17A secretion by CD4(+) T cells as compared with that of control BMDMs. We then found that PGE2 production and COX-2 expression by BMDMs from WSX-1-deficient mice was increased compared to control macrophages in response to LPS. The enhanced production of IFN-γ and IL-17A was abolished by EP2 and EP4 antagonists, demonstrating PGE2 was responsible for enhanced cytokine production. Murine WSX-1-expressing Raw264.7 cells (mWSX-1-Raw264.7) showed phosphorylation of both STAT1 and STAT3 in response to IL-27 and produced less amounts of PGE2 and COX-2 compared to parental RAW264.7 cells. STAT1 knockdown in parental RAW264.7 cells and STAT1-deficiency in BMDMs showed higher COX-2 expression than their respective control cells. Collectively, our result indicated that IL-27/WSX-1 regulated PGE2 secretion via STAT1-COX-2 pathway in macrophages and affected helper T cell response in a PGE2-mediated fashion.

Syk-dependent signaling pathways in neutrophils and macrophages are indispensable in the pathogenesis of anti-collagen antibody-induced arthritis.

Spleen tyrosine kinase (Syk) is associated with Fcγ receptors (FcγRs) and transmits activation signals through FcγRs in myeloid cells. Thus, application of drugs to inhibit Syk activity can affect the development of immune diseases mediated by autoantibodies, while unexpected systemic effects by the inhibition may be concerned because Syk has multiple physiological functions. We used tamoxifen-inducible systemic conditional Syk knockout (KO) mice to evaluate the role of Syk in the pathogenesis of autoimmune arthritis and to investigate the systemic effects of Syk deletion. In a collagen antibody-induced arthritis model, Syk KO mice were almost completely protected from disease induction and showed significantly attenuated accumulation of neutrophils and macrophages in the joints. Syk-deleted macrophages showed less IL-6 and MCP-1 production upon FcγR ligation and exhibited reduced FcγR-mediated phagocytosis in vitro. Syk-deleted macrophages produce more RANTES upon FcγR ligation, indicating a Syk-independent signaling through the FcγR. We further found that both wild-type and Syk-deleted macrophages induced neutrophil chemotaxis upon FcγR ligation in vitro, and air-pouch model demonstrated that Syk-deleted neutrophils have a potential to infiltrate into local tissues in response to collagen and anti-collagen antibodies. However, Syk-deleted neutrophils exhibited greatly decreased neutrophil extracellular traps formation and FcγR-mediated phagocytosis. Our results indicated that Syk deficiency rendered mice completely unresponsive to immune activation by anti-collagen antibodies with disabling one pathway of FcγR-mediated signaling that was crucial for arthritis induction.

Effects of the delay and duration of self-generated wind on behavioral compensation in unilaterally cercus-ablated crickets, Gryllus bimaculatus.

The effects of the delay and duration of wind self-generated during walking on the compensational recovery of escape direction were investigated in unilaterally cercus-ablated crickets, Gryllus bimaculatus. Artificial self-generated winds (self-stimulations; hereafter, SSts) from a nozzle set in front of a cricket placed on a styrofoam ball for stationary walking were used for training after unilateral cercus ablation. The delay and duration of artificial SSts were separately controlled. When the stimulus duration was fixed to 100 msec, the crickets trained with artificial SSts of 1000 msec delay showed a compensational recovery of the escape direction. However, no such compensational recovery was observed in crickets trained with artificial SSts of 1200, 1500, and 2000 msec delays. The relationship between the delay and duration of artificial SSts for compensational recovery was investigated. An artificial SSt with a longer delay required a longer-duration air current to cause a recovery of the escape direction. In contrast, an artificial SSt with a shorter delay was effective even when the duration was short. On the basis of the results obtained in the present study, we propose a hypothesis to explain the initial step for the compensation, that is, how the delay and duration of SSts are traded in terms of the compensational recovery of the escape direction.

[Pharmacological actions of anifrolumab (Saphnelo®) and clinical trial results as a treatment for systemic lupus erythematosus].

Systemic lupus erythematosus (SLE) is an autoimmune disease which causes damaging inflammation in multiple organs via the accumulation of immune complexes. SLE pathogenesis is associated with type I interferons (IFNs), which are central and reflective of disease activity in SLE. Even before clinical development of disease, genetic and environmental contributions to IFN production lead to abnormal innate and adaptive immune activation. Through the Janus kinase-signal transducer and activator of transcription signaling pathway, IFN play a central role in the immunopathogenicity of SLE. Thus, IFN-blocking therapy may be used to regulate inflammation in individuals with SLE. Food and Drug Administration (FDA)-approved anifrolumab (Saphnelo®), which is a human IgG1κ monoclonal antibody that binds to subunit 1 of the type I interferon receptor with high specificity and affinity, was also approved for the treatment of adult patients with moderate to severe SLE who are receiving standard therapy by Pharmaceuticals and Medical Device Agency (PMDA), in Japan in September 2021; anifrolumab is administered as an intravenous infusion, 300 mg over a 30-minute period, every 4 weeks. In this article, we reviewed the actions of type I IFN and anifrolumab as a treatment for SLE.

Comparison of microsomal prostaglandin E synthase-1 deletion and COX-2 inhibition in acute cardiac ischemia in mice.

The aim of the present study was to compare the effects of genetic mPGES-1 loss and COX-2 inhibition on myocardial damage after coronary occlusion. mPGES-1(-/-) mice and their wild-type littermates were injected with vehicle or COX-2 inhibitor (celecoxib), and 30min later the left coronary artery was surgically occluded. At 24h, myocardial infarct (MI) volume was measured histologically. Post-MI survival was reduced in WT mice receiving celecoxib (12/20) compared with vehicle-treated controls (12/12) or the loss of mPGES-1 (13/13) together with increased phosphokinase (CPK) and cardiac troponin-I release. Endogenous mPGES-1 expression was unchanged by ischemia in WT mice and absent in mPGES-1(-/-) hearts. COX-2 expression was markedly increased at 24h after MI in WT hearts; this upregulation was largely attenuated in mPGES-1(-/-) mice. We conclude that loss of mPGES-1 prevents the upregulation of COX-2 after myocardial infarct, and in contrast to inhibition of COX-2, does not increase ischemic myocardial damage.

Development of Diagnostic Techniques for Early Rheumatoid Arthritis Using Positron Emission Tomography with [11C]PK11195 and [11C]Ketoprofen Tracers.

PURPOSE: In vivo detection of pathological insults during the early stages of rheumatoid synovitis is essential to allow early anti-inflammatory treatment for prevention of joint destruction. Whether rheumatoid synovitis pathology and the efficacy of therapies can be visualized by positron emission tomography (PET) tracers specific to the inflammatory process was investigated. PROCEDURES: Using a collagen-induced experimental rat model of rheumatoid arthritis, in vivo imaging using the PET tracers [11C]PK11195, which binds to the translocator protein mainly expressed on myeloid cells, and [11C]ketoprofen, for cyclooxygenase imaging, was performed. To evaluate therapeutic efficacy, model animals were administered the tumour necrosis factor alpha blocker etanercept subcutaneously. RESULTS: [11C]PK11195 and [11C]ketoprofen uptakes were significantly higher in inflamed paws of collagen-induced arthritis rats than in normal rats. The data showed a correlation between tracer uptake values and paw swelling. After treatment with etanercept, [11C]ketoprofen uptake was significantly lower in treated animals than in untreated ones, whereas [11C]PK11195 uptake in the inflamed regions was comparable to that in the untreated group. CONCLUSIONS: With [11C]PK11195 and [11C]ketoprofen tracers, non-invasive in vivo PET imaging for rheumatoid synovitis can provide diagnostic evidence of early synovitis and allow monitoring inflammatory cell activity during treatment.

Detection of the p110 beta subunit of phosphatidylinositol 3-kinase complexed with neutral endopeptidase.

BACKGROUND: Neutral endopeptidase 24.11 (NEP) is a cell-surface peptidase that inactivates a variety of neuropeptide substrates. In addition to catalytic activity, NEP can exert biological effects through protein-protein interactions. We previously reported that NEP directly associated with tyrosine-phosphorylated Lyn kinase, and with the p85 subunit of the phosphatidylinositol 3-kinase (PI3 kinase) resulting in an NEP-Lyn-PI3 kinase protein complex. MATERIALS AND METHODS: In this report, we investigated the association of NEP with cytoplasmic proteins using ProteinChip Array, surface enhanced laser desorption/ionization (SELDI) technology combined with time-of-flight mass spectrometry, as well as immunoprecipitation and Western blottings. RESULTS: Using immunocapture on the ProteinChip surface, we identified a 122 kDa protein which associates with NEP derived from LNCaP cell lysates which had the identical molecular weight as the beta-subunit of p110 subunit of phosphatidylinositol 3-kinase. The identity of the p110 beta was confirmed by Western blot analysis of NEP and p110 beta immunoprecipitates using monoclonal antibodies specific for NEP and p110 beta. CONCLUSION: These data confirm the association of phosphatidylinositol 3-kinase (consisting of the p85 adaptor and p110 beta-subunit) with NEP. Furthermore, this work demonstrates the ability of mass spectrometry to identify proteins interacting with NEP and potentially other cell-surface peptidases.

An ITAM-Syk-CARD9 signalling axis triggers contact hypersensitivity by stimulating IL-1 production in dendritic cells.

A variety of reactive organic compounds, called haptens, can cause allergic contact dermatitis. However, the innate immune mechanisms by which haptens stimulate dendritic cells (DCs) to sensitize T cells remain unclear. Here we show that the coupling of ITAM-Syk-CARD9 signalling to interleukin-1 (IL-1) secretion in DCs is crucial for allergic sensitization to haptens. Both MyD88 and Caspase recruitment domain-containing protein 9 (CARD9) signalling are required for contact hypersensitivity (CHS). Naïve T cells require signals received through IL-1R1-MyD88 for effector differentiation, whereas DCs require CARD9 and spleen tyrosine kinase (Syk) signalling for hapten-induced IL-1α/ß secretion and their ability to prime T cells. DC-specific deletion of CARD9, DAP12, Syk or NLRP3, but not MyD88, is sufficient to abolish CHS. All tested haptens, but not irritants, can induce Syk activation, leading to both the CARD9/BCL10-dependent pro-IL-1 synthesis (signal1) and reactive oxygen species-mediated NLRP3 inflammasome activation (signal2), required for IL-1 secretion. These data unveil an innate immune mechanism crucial for allergic contact sensitization to chemical compounds.

Dysregulation of suppressor of cytokine signaling 3 in keratinocytes causes skin inflammation mediated by interleukin-20 receptor-related cytokines.

Homeostatic regulation of epidermal keratinocytes is controlled by the local cytokine milieu. However, a role for suppressor of cytokine signaling (SOCS), a negative feedback regulator of cytokine networks, in skin homeostasis remains unclear. Keratinocyte specific deletion of Socs3 (Socs3 cKO) caused severe skin inflammation with hyper-production of IgE, epidermal hyperplasia, and S100A8/9 expression, although Socs1 deletion caused no inflammation. The inflamed skin showed constitutive STAT3 activation and up-regulation of IL-6 and IL-20 receptor (IL-20R) related cytokines, IL-19, IL-20 and IL-24. Disease development was rescued by deletion of the Il6 gene, but not by the deletion of Il23, Il4r, or Rag1 genes. The expression of IL-6 in Socs3 cKO keratinocytes increased expression of IL-20R-related cytokines that further facilitated STAT3 hyperactivation, epidermal hyperplasia and neutrophilia. These results demonstrate that skin homeostasis is strictly regulated by the IL-6-STAT3-SOCS3 axis. Moreover, the SOCS3-mediated negative feedback loop in keratinocytes has a critical mechanistic role in the prevention of skin inflammation caused by hyperactivation of STAT3.

The effects of microsomal prostaglandin E synthase-1 deletion in acute cardiac ischemia in mice.

The goal of the present study was to assess how genetic loss of microsomal prostaglandin E(2) synthase-1 (mPGES-1) affects acute cardiac ischemic damage after coronary occlusion in mice. Wild type (WT), heterozygous (mPGES-1(+/-)), and homozygous (mPGES-1(-/-)) knockout mice were subjected to left coronary artery occlusion. At 24h, myocardial infarct (MI) volume was measured histologically. Post-MI survival, plasma levels of creatine phosphokinase (CPK) and cardiac troponin-I, together with MI size, were similar in WT, mPGES-1(+/-) and mPGES-1(-/-) mice. In contrast, post-MI survival was reduced in mPGES-1(-/-) mice pretreated with I prostanoid receptor (IP) antagonist (12/16) compared with vehicle-treated controls (13/13 mPGES-1(-/-)) together with increased CPK and cardiac troponin-I release. The deletion of mPGES-1 in mice results in increased prostacyclin I(2) (PGI(2)) formation and marginal effects on the circulatory prostaglandin E(2) (PGE(2)) level. We conclude that loss of mPGES-1 results in increased PGI(2) formation, and in contrast to inhibition of PGI(2), without worsening acute cardiac ischemic injury.