Mastitis, inflammation of the mammary gland, is the most costly common disease in the dairy industry, and is caused by mammary pathogenic bacteria, including Escherichia coli. The bacteria invade the mammary alveolar lumen and disrupt the blood-milk barrier. In normal mammary gland, alveolar epithelial tight junctions (TJs) contribute the blood-milk barrier of alveolar epithelium by blocking the leakage of milk components from the luminal side into the blood serum. In this study, we focused on claudin subtypes that participate in the alveolar epithelial TJs, because the composition of claudins is an important factor that affects TJ permeability. In normal mouse lactating mammary glands, alveolar TJs consist of claudin-3 without claudin-1, -4, and -7. In lipopolysaccharide (LPS)-induced mastitis, alveolar TJs showed 2-staged compositional changes in claudins. First, a qualitative change in claudin-3, presumably caused by phosphorylation and participation of claudin-7 in alveolar TJs, was recognized in parallel with the leakage of fluorescein isothiocyanate-conjugated albumin (FITC-albumin) via the alveolar epithelium. Second, claudin-4 participated in alveolar TJs with claudin-3 and claudin-7 12 h after LPS injection. The partial localization of claudin-1 was also observed by immunostaining. Coinciding with the second change of alveolar TJs, the severe disruption of the blood-milk barrier was recognized by ectopic localization of β-casein and much leakage of FITC-albumin. Furthermore, the localization of toll-like receptor 4 (TLR4) on the luminal side and NFκB activation by LPS was observed in the alveolar epithelial cells. We suggest that the weakening and disruption of the blood-milk barrier are caused by compositional changes of claudins in alveolar epithelial TJs through LPS/TLR4 signaling.

Mice were infected intravenously with a sublethal dose of Listeria monocytogenes cells and then levels of tumor necrosis factor (TNF), interleukin-6 (IL-6), and gamma interferon (IFN-y) in the bloodstreams, spleens, and livers were monitored. The maximum level of TNF was detected at 72 h in the spleens and livers, but TNF was never detected in the bloodstreams. IL-6 appeared in the bloodstreams and spleens and peaked at 48 h. The maximum level of IFN-y could be detected in all three specimens, and the highest titer was shown in the spleens. Endogenous TNF production was suppressed by in vivo administration of anti-CD4 monoclonal antibody (MAb) or anti-asialo GM1 antibody but not by anti-CD8 MAb, whereas none of these antibodies suppressed endogenous IL-6 production. Endogenous production of neither IL-6 nor IFN-y was inhibited in rabbit antirecombinant mouse TNF-a antibody-treated mice. Similarly, production of TNF and IL-6 did not decrease in anti-mouse IFN-y MAb-treated animals, but TNF production was augmented in these animals. These results suggest that the these endogenous cytokines are produced by different mechanisms in L. monocytogenes infection. Complete elimination of Listeria monocytogenes, a facul-523 on July 16, 2020 by guest http://iai.asm.org/ Downloaded from INFECT. IMMUN. on July 16, 2020 by guest http://iai.asm.org/ Downloaded from

It has been presumed that gamma interferon (IFN-gamma), which plays an essential role in antilisterial resistance, is produced late in Listeria monocytogenes infection. In the present study, however, IFN-gamma was detected in the bloodstreams and spleens of mice from days 1 to 4 of L. monocytogenes infection by both a double-sandwich enzyme-linked immunosorbent assay and an immunohistochemical technique, suggesting that endogenous IFN-gamma is produced early but not late in L. monocytogenes infection.

The effects of in vivo administration of antibodies against T-cell subsets and asialo GM1 (ASGM1)-bearing ceUs on endogenous gamma interferon (IFN-,y) production and host defense in Listeria monocytogenes-infected mice were investigated. Endogenous IFN-y titers in the bloodstreams and spleen extracts of mice on day 2 of infection were partially suppressed by administration of rabbit anti-ASGM1 antibody, but not by anti-CD4 monoclonal antibody (MAb) or anti-CD8 MAb. Of the different combinations of these three antibodies, the most suppressive effect on IFN--y production was observed after administration of anti-CD4 MAb and anti-ASGM1 antibody, although anti-CD8 MAb combined with anti-CD4 MAb partially inhibited IFN-y production. In contrast, antilisterial resistance was suppressed by the administration of anti-CD8 MAb but not by anti-CD4 MAb or anti-ASGM1 antibody. Antilisterial resistance in mice in which both CD4+ cells and ASGM1+ cells had been depleted was performed as efficiently as in normal mice in spite of the fact that endogenous IFN-y production was markedly suppressed. Furthermore, these mice also eliminated L. monocytogenes cells efficiently from the spleens even when they were pretreated with anti-mouse IFN-,y MAb.These results indicate that CD4+ T cells, CD8+ T cells, and ASGM1+ cells are all responsible for endogenous * Corresponding author. IFN--y-producing cells, in L. monocytogenes infection by in vivo injection of antibodies against T-cell subsets and asialo GM1 (ASGM1)-bearing cells, which mainly correspond to NK cells. In this report, we provide evidence that CD4+ T cells, CD8+ T cells, and ASGM1+ cells are all responsible for endogenous IFN-y production. Our results demonstrate further that antilisterial resistance and endogenous IFN--y production are not absolutely correlated. MATERIALS AND METHODSMice. Female ddY mice (age, 5 to 7 weeks; obtained from SLC, Hamamatsu, Shizuoka, Japan) were used.Bacteria. L. monocytogenes lb 1684 was prepared as described previously (25). The concentration of washed cells was adjusted spectrophotometrically at 550 nm. Mice were infected intravenously with 0.2 ml of a solution containing 2 x 104 CFU of viable L. monocytogenes cells in 0.01 M phosphate-buffered saline (PBS; pH 7.4).Antibodies. Hybridoma cells secreting MAbs directed against CD4 (L3T4) (GK1.5, rat immunoglobulin G2b) (8) and CD8 (Lyt-2) (53-6.72, rat immunoglobulin G2a) (16) antibodies were kindly provided by T. Koike, School of Medicine, Chiba University, Chiba, Japan. A rat anti-mouse IFN--y-secreting hybridoma (R4-6A2, immunoglobulin Gl) (30) was donated by Y. Watanabe, Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan. These MAbs were prepared from ascites fluid in Pristane-primed CD-1 nulnu mice. Partial purification by 50% (NH4)2SO4 precipitation was followed by exhaustive dialysis against PBS. Rabbit anti-ASGM1 antibody was prepared and partially purified by 50% (NH4)2SO4 precipitation as described previously (22). The antibodies were aliquoted and stored at -700C.

Nerve cells on the ventrolateral side of the periaqueductal gray have neural communications with the pontine micturition center bilaterally and they regulate micturition.