Prostaglandin E2-Induced Immune Suppression via Cytotoxic T-Lymphocyte Antigen 4 in Paratuberculosis.

Paratuberculosis is a chronic enteritis of ruminants caused by the facultative intracellular pathogen Mycobacterium avium subsp. paratuberculosis. The Th1 response inhibits the proliferation of M. avium subsp. paratuberculosis during the early subclinical stage. However, we have previously shown that immune inhibitory molecules, such as prostaglandin E2 (PGE2), suppress M. avium subsp. paratuberculosis-specific Th1 responses as the disease progresses. To date, the mechanism underlying immunosuppression during M. avium subsp. paratuberculosis infection has not been elucidated. Therefore, in the present study, we investigated the function of cytotoxic T-lymphocyte antigen 4 (CTLA-4) expressed by peripheral blood mononuclear cells (PBMCs) from cattle with paratuberculosis because CTLA-4 expression is known to be elevated in T cells under an M. avium subsp. paratuberculosis experimental infection. M. avium subsp. paratuberculosis antigen induced CTLA-4 expression in T cells from cattle experimentally infected with M. avium subsp. paratuberculosis. Interestingly, both PGE2 and an E prostanoid 4 agonist also induced CTLA-4 expression in T cells. In addition, a functional assay with a bovine CTLA-4-immunogobulin fusion protein (CTLA-4-Ig) indicated that CTLA-4 inhibited gamma interferon (IFN-γ) production in M. avium subsp. paratuberculosis-stimulated PBMCs, while blockade by anti-bovine CTLA-4 monoclonal antibody increased the secretion of IFN-γ and tumor necrosis factor alpha production in these PBMCs. These preliminary findings show that PGE2 has immunosuppressive effects via CTLA-4 to M. avium subsp. paratuberculosis. Therefore, it is necessary to clarify in the future whether CTLA-4-mediated immunosuppression facilitates disease progression of paratuberculosis in cattle.

Intravitreal ranibizumab improves macular sensitivity in patients with central retinal vein occlusion and macula edema.

BACKGROUND: Patients with central retinal vein occlusion (CRVO) and macular edema often are treated by intravitreal ranibizumab injection (IRI). The role of changes in macular sensitivity in the positive effects of IRI on visual functions is unclear. Therefore, we assessed the relationship between macular sensitivity and improvement of visual functions. METHODS: We included 15 eyes of 15 patients with treatment-naïve CRVO and followed patients for 6 months after pro re nata IRI. IRI was repeated if the central macular thickness was greater than or equal to 300 µm. Microperimetry-3 was used to measure macular sensitivity within the central 1-mm, 3-mm, and 6-mm fields before and monthly for 6 months after IRI. RESULTS: IRI significantly improved mean macular sensitivity over time within the central 1-mm, 3-mm, and 6-mm fields (all P < 0.001). None of the fields showed significant differences in the change of mean macular sensitivity between patients with little improvement in best corrected visual acuity (BCVA; i.e., in patients with a change in logarithm of the minimum angle of resolution [logMAR] BCVA < 0.3) and those with marked improvement in BCVA (change in logMAR BCVA > 0.3). The mean macular sensitivity before IRI showed correlations with the improvement of macular sensitivity in every field. CONCLUSION: These findings suggest that IRI improves macular sensitivity in patients with CRVO and macular edema independent of any improvement in BCVA and that macular sensitivity before treatment is associated with improvement of macular sensitivity after treatment.

Effects of bovine tumor necrosis factor alpha decoy receptors on cell death and inflammatory cytokine kinetics: potential for bovine inflammation therapy.

BACKGROUND: Refractory diseases, including bacterial infections, are causing huge economic losses in dairy farming. Despite efforts to prevent and treat those diseases in cattle, including the use of antimicrobials, it is not well controlled in the field. Several inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), play important roles in disease progression; thus, blocking these cytokines can attenuate the acute and sever inflammation and may be a novel strategy for treatment. However, biological drugs targeting inflammatory cytokines have not been used in cattle. Therefore, in this study, bovine sTNFR1 and sTNFR2 IgG1 Fc-fusion proteins (TNFR1-Ig and TNFR2-Ig) were produced, and their anti-inflammatory functions were analyzed in vitro, to develop decoy receptors for bovine TNF-α. RESULTS: Both TNFR1-Ig and TNFR2-Ig were shown to bind with TNF-α, and TNFR2-Ig showed higher affinity toward TNF-α than TNFR1-Ig. We next stimulated murine fibroblast-derived cells (L929 cells) with TNF-α to induce cell death and analyzed cell viability in the presence of TNFR-Ig proteins. Both TNFR1-Ig and TNFR2-Ig suppressed TNF-α-induced cell death, significantly improving cell viability. In addition, cell death induced by TNF-α was suppressed, even at low TNFR2-Ig concentrations, suggesting TNFR2-Ig has higher activity to suppress TNF-α functions than TNFR1-Ig. Finally, to examine TNFR2-Ig's anti-inflammatory, we cultured peripheral blood mononuclear cells from cattle with TNF-α in the presence of TNFR2-Ig and analyzed the gene expression and protein production of the inflammatory cytokines IL-1ß and TNF-α. TNFR2-Ig significantly reduced the gene expression and protein production of these cytokines. Our results suggest that TNFR2-Ig inhibits inflammatory cytokine kinetics by blocking TNF-α to transmembrane TNFR, thereby attenuating excessive inflammation induced by TNF-α. CONCLUSIONS: Collectively, the findings of this study demonstrated the potential of TNFR2-Ig as a novel therapeutic for inflammatory diseases, such as bovine clinical mastitis. Further investigation is required for future clinical application.

Effect of chronic administration of ritonavir on function of cytochrome P450 3A and P-glycoprotein in rats.

Ritonavir (RTV) is well known as an inhibitor of many drugs that are metabolized by cytochrome P450 (CYP) 3A or fluxed via P-glycoprotein (Pgp), although it is also reported that RTV is a potent inducer for them. In this study, to elucidate these contradictory phenomena, functional changes of CYP3A or Pgp during chronic administration of RTV were examined in rats. After pretreatment with RTV for indicated days (day 3-day 14), rats were used in the experiments. The area under the plasma drug concentration vs. time curve (AUC(0-infinity)) after oral administration of RTV (20 mg/kg) to these rats showed an RTV-treatment period-dependent decrease, and the mean AUC(0-infinity) of RTV in Day 14 rats decreased significantly by 57% as compared to the control. The AUC(0-infinity) after intravenous (i.v.) administration of RTV to Day 3 and Day 5 rats increased significantly by 28% and 22%, respectively, while there were no significant changes in the AUC(0-infinity) in Day 7 and Day 14 rats as compared to the control. As for i.v. administration of erythromycin (EM) or midazolam (MDZ) to RTV-treated rats, the AUC(0-infinity)in Day 3 and Day 5 rats increased significantly as compared to the control, while in Day 7 rats and rifampicin-treated rats, the AUC(0-infinity) of EM decreased significantly by 82% and 42%, respectively, as compared to the control. For MDZ, there were no significant changes in the AUC(0-infinity) in Day 7 or Day 14 rats. After i.v. administration of rhodamine123 (Rho123), the excretion clearances from blood circulation to the intestinal lumen and the biliary excretion clearances in Day 14 rats increased markedly by 2.2-fold and 2.6-fold as compared to the control. It has been confirmed that RTV is not only a potent inhibitor but also a potent inducer of CYP3A, and that RTV is a potent inducer of intestinal Pgp. This property of RTV is responsible for regulating the oral bioavailability of drugs that are mediated by CYP3A and Pgp.