Background: Microsomal prostaglandin E synthase-1 (mPGES-1) is a key enzyme that acts downstream of cyclooxygenase and plays a major role in inflammation by converting prostaglandin (PG) H₂to PGE₂. The present study investigated the effect of genetic deletion of mPGES-1 on the development of immunologic responses to experimental colitis induced by dextran sodium sulfate (DSS), a well-established model of inflammatory bowel disease (IBD).Methods: Colitis was induced in mice lacking mPGES-1 (mPGES-1^−/−mice) and wild-type (WT) mice by administering DSS for 7 days. Colitis was assessed by body weight loss, diarrhea, fecal bleeding, and histological features. The colonic expression of mPGES-1 was determined by real-time PCR, western blotting, and immunohistochemistry. The impact of mPGES-1 deficiency on T cell immunity was determined by flow cytometry and T cell depletionin vivo.Results: After administration of DSS, mPGES-1^−/−mice exhibited more severe weight loss, diarrhea, and fecal bleeding than WT mice. Histological analysis further showed significant exacerbation of colonic inflammation in mPGES-1^−/−mice. In WT mice, the colonic expression of mPGES-1 was highly induced on both mRNA and protein levels and colonic PGE₂increased significantly after DSS administration. Additionally, mPGES-1 protein was localized in the colonic mucosal epithelium and infiltrated inflammatory cells in underlying connective tissues and the lamina propria. The abnormalities consistent with colitis in mPGES-1^−/−mice were associated with higher expression of colonic T-helper (Th)17 and Th1 cytokines, including interleukin 17A and interferon-γ. Furthermore, lack of mPGES-1 increased the numbers of Th17 and Th1 cells in the lamina propria mononuclear cells within the colon, even though the number of suppressive regulatory T cells also increased. CD4⁺T cell depletion effectively reduced symptoms of colitis as well as colonic expression of Th17 and Th1 cytokines in mPGES-1^−/−mice, suggesting the requirement of CD4⁺T cells in the exacerbation of DSS-induced colitis under mPGES-1 deficiency.Conclusions: These results demonstrate that mPGES-1 is the main enzyme responsible for colonic PGE₂production and deficiency of mPGES-1 facilitates the development of colitis by affecting the development of colonic T cell–mediated immunity. mPGES-1 might therefore impact both the intestinal inflammation and T cell–mediated immunity associated with IBD.

Necrotizing pneumonia caused by Panton-Valentine leukocidin (PVL)-positive community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has high mortality, and is currently a serious clinical issue. PVL is a two-component toxin consisting of LukS-PV and LukF-PV. PVL was shown to cause necrosis in target cells by forming pores consisting of an octamer comprised of LukS-PV and LukF-PV. However, because of the specificity of PVL toward several target cells and species, the detailed action of PVL remains controversial. Therefore, we focused on necrotizing pneumonia caused by PVL-positive Staphylococcus aureus and clarified the effects of PVL on alveolar macrophages, which play a central role in innate immunity in the alveolar space. We constructed recombinant PVL (rPVL) components and stimulated alveolar macrophages isolated from rabbits, and then evaluated the cytotoxicity and pro-inflammatory cytokine release. Recombinant LukS-PV (rLukS-PV), but not recombinant LukF-PV (rLukF-PV), induced pro-inflammatory cytokine release. Especially, TNF-α release was mediated via the C5a receptor (C5aR) expressed in rabbit alveolar macrophages and rPVL, consisting of rLukS-PV and rLukF-PV, was highly toxic to rabbit alveolar macrophages via the same receptor. Our results, which reveal the action of PVL via C5aR on alveolar macrophages, may be useful for understanding the mechanism of necrotizing pneumonia caused by PVL.

Background: Hormone therapy and chemotherapy are not effective for castrate-resistant prostate cancer, thus development of novel treatment strategies is required. Gene therapy involving transient high-copy transfection of interleukin (IL)-24 with an adenoviral vector can exert antitumor activity; however, the effects of stable IL-24 transfection are not fully understood. The aim of this study was to investigate the effects of IL-24 overexpression in prostate cancer cells, in vitro. Materials and Methods: DU145 cells were transfected the IL-24 gene using a retroviral vector. Apoptosis induction was investigated by the cell death detection ELISA, and the gene expression was analyzed by real time RT-PCR. Results: IL-24 transduction suppressed the growth of prostate cancer and induced tumor cell apoptosis. In addition, up-regulation of epithelial markers and down-regulation of mesenchymal markers were noted, suggesting that tumor aggressiveness was reduced. Conclusion: Introduction of IL-24 displays antitumor activity both by induction of apoptosis and regulation of anchorage dependence.

Microsomal prostaglandin E synthase-1 (mPGES-1) is an isozyme of the prostaglandin (PG) E synthase that acts downstream of cyclooxygenase and catalyzes the conversion of PGH₂ to PGE₂. The impact of genetic deletion of mPGES-1 on the development of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis, a well-established model of inflammatory bowel disease (IBD), was investigated in this study. After administration of TNBS, mice deficient in mPGES-1 (mPGES-1^−/− mice) showed more severe colitis than did wild-type (WT) mice. Histological examination revealed that mPGES-1^−/− mice had markedly exacerbated symptoms of colitis. mPGES-1 expression was detectable in the colons of WT mice at both the mRNA and protein levels. Lack of mPGES-1 resulted in marked reduction of colonic PGE₂ production. Our study also showed a significant increase in colonic expression of interleukin-17A (IL-17A), as well as interferon γ (IFNγ) and tumor necrosis factor α, during colitis in mPGES-1^−/− mice compared with that in WT mice. Furthermore, loss of mPGES-1 increased the populations of IL-17A-producing T-helper (Th) 17 and IFNγ-producing Th1 cells in mesenteric lymph nodes. These results suggest that mPGES-1 is the main enzyme responsible for colonic PGE₂ production and deficiency of mPGES-1 facilitates the development of colitis and T-cell-mediated immunity. mPGES-1 might, therefore, impact T-cell-related immune response associated with IBD.

The antiviral efficacy of cell-extracts (CEs) derived from cypress (Chamaecyparis obtusa (Siebold & Zucc.) Endl., C. obtusa) and cedar (Cryptomeria japonica (Thunb. ex. L.) D.Don, C. japonica) was assessed using phi6 and MS2 bacteriophages, which are widely accepted surrogate models for enveloped and non-enveloped viruses, in order to verify their potential use as antiviral agents. Our results indicate that CEs derived from C. obtusa are dominantly composed of terpinen-4-ol (18.0%), α-terpinyl acetate (10.1%), bornyl acetate (9.7%), limonene (7.1%), and γ-terpinene (6.7%), while CEs derived from C. japonica are dominantly composed of terpinen-4-ol (48.0%) and α-pinene (15.9%), which exhibited robust antiviral activity against phi6 bacteriophage. Both CEs successfully inactivated the phi6 bacteriophage below the detection limit (10 PFU/mL) within a short exposure time of 30 s (log reduction value, LRV > 4). Through exposure experiments utilizing CEs with content ratios prepared via 2-fold serial dilutions (ranging from 3.13% to 100%), we demonstrated that the antiviral effect could be sustained up to a concentration of 25% (C. obtusa LRV = 3.8, C. japonica LRV > 4.3 at a 25% CE content ratio for each species). However, CEs with content ratios below 12.5% did not produce a significant reduction in bacteriophage concentration and consequently lost their antiviral effects. Conversely, both CEs did not exhibit antiviral activity against MS2 bacteriophage, a non-enveloped virus. Our findings reveal for the first time the potential of CEs derived from C. obtusa and C. japonica for use as antiviral agents specifically targeting enveloped viruses.

Background: Numerous biomarkers have been identified for the diagnosis of periprosthetic joint infection (PJI), but no single biomarker has been proven to have definitive accuracy. Alpha-defensin is an excellent biomarker that is included as a minor criterion in the 2nd International Consensus Meeting (ICM) PJI diagnostic criteria; however, its high cost limits its accessibility at many general medical facilities. Consequently, alternative biomarkers for PJI diagnosis are under investigation. Myeloperoxidase (MPO), an enzyme with microbicidal properties through the catalysis of hypochlorous acid production, has emerged as a promising alternative. MPO has previously been reported as an effective biomarker for PJI. In the present study, we conducted a rapid MPO test as a point-of-care test (POCT) and evaluated its diagnostic utility. Methods: Patients with a suspected infection after total joint arthroplasty were categorized into the PJI or aseptic failure groups according to the 2nd ICM PJI diagnostic criteria. MPO and alpha-defensin levels in synovial fluid that was collected during surgery were quantified using an enzyme-linked immunosorbent assay (ELISA), and their diagnostic accuracy was compared. Additionally, an MPO POCT was conducted, and its diagnostic accuracy was assessed. Results: The investigation included 23 patients with PJI and 23 with aseptic failure. All were Japanese. MPO and alpha-defensin ELISAs exhibited a strong correlation, and, at the optimal cutoff, both tests demonstrated a sensitivity of 0.957 and a specificity of 0.957. The MPO POCT produced results in just 10 minutes and achieved a sensitivity of 1.00 and a specificity of 0.913. Conclusions: The MPO ELISA demonstrated high diagnostic accuracy for PJI, equivalent to that of the alpha-defensin test. Furthermore, the MPO POCT showed similarly high diagnostic accuracy. The MPO POCT is a promising and rapid tool for diagnosing PJI and could serve as an alternative to the alpha-defensin test. Level of Evidence: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.