g(m1)-ganglioside and Sepsis

We previously showed that beta2-microglobulin knockout mice treated with anti-asialoGM1 (beta2M/alphaAsGM1 mice) exhibit less hypothermia, reduced production of proinflammatory cytokines, less metabolic acidosis, and improved survival after cecal ligation and puncture (CLP) compared with wild-type mice. The present study was designed to assess hemodynamics and left ventricular contractility at 18 h after CLP. Arterial pressure was measured by carotid artery cannulation, and left ventricular pressure-volume loops were obtained by insertion of a 1.4-F conductance catheter into the left ventricle. Heart rate, stroke volume, and cardiac output were not significantly different between wild-type and beta2M/alphaAsGM1 mice after CLP. However, beta2M/alphaAsGM1 mice exhibited improved mean arterial pressure and systemic vascular resistance compared with wild-type mice. Myocardial function was also better preserved in beta2M/alphaAsGM1 mice as indicated by improved left ventricular pressure development over time, time-varying maximum elastance, endsystolic pressure-volume relationship, and preload recruitable stroke work. Overall, this study shows that cardiovascular collapse characterized by hypotension, myocardial depression, and low systemic vascular resistance occurs after CLP in wild-type mice. However, beta2M/alphaAsGM1 mice exhibit improved hemodynamics and cardiac contractile function after CLP that may account, in part, for our previously observed survival benefit.

Topics: Abdomen; Acute Disease; Animals; beta 2-Microglobulin; Blood Pressure; Female; G(M1) Ganglioside; Hemodynamics; Hypotension; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardial Contraction; Sepsis; Vascular Resistance; Ventricular Function, Left

Natural killer (NK) cells have a well-established role in host defense against viral infections and malignancies. However, their function in bacterial infection and sepsis is poorly defined. We hypothesized that NK cells, as a major producer of interferon-gamma during sepsis, would be important in host defense against bacterial infections. Cecal ligation and puncture (CLP) was performed on Swiss Webster mice depleted of NK cells by pretreatment with anti-asialo GM1 and control mice given immunoglobulin G (IgG) antibody. NK cell-depleted mice had significantly higher anaerobic bacterial counts in the liver and peritoneal lavage fluid, as well as higher aerobic counts in the liver and blood 4 h after CLP. Macrophage phagocytosis, nitric oxide production, and interleukin (IL)-6 levels at 4 h were also decreased in mice depleted of NK cells compared with controls. Greater neutrophil influx into the peritoneum, indicated by higher myeloperoxidase levels, was also seen in NK cell-depleted mice. At 8 and 18 h after CLP, bacterial counts were similar between groups, and overall survival rates were not significantly different. Peritoneal IL-12 levels significantly increased by 18 h in normal mice, but not in NK cell-depleted animals. Our data suggest that NK cells participate in the early local and systemic eradication of bacteria and regulation of IL-12 during polymicrobial sepsis. These effects are likely due to their interactions with macrophages.

Topics: Animals; Bacteria; Cell Movement; Chemokine CXCL2; Flow Cytometry; G(M1) Ganglioside; Inflammation; Interleukin-6; Killer Cells, Natural; Macrophages; Mice; Monokines; Neutrophils; Nitric Oxide; Peritonitis; Peroxidase; Phagocytosis; Sepsis; Time Factors

beta 2 microglobulin knockout (beta2M-/-) mice lack CD8+ T and natural killer T cells. We hypothesized that beta 2M-/- mice are resistant to lethal intraabdominal sepsis. To test this hypothesis, mortality, cytokine production, and physiologic function were assessed in beta 2M-/- mice during sepsis caused by cecal ligation and puncture (CLP). beta 2M-/- mice survived significantly longer than wild-type mice after CLP but ultimately exhibited 100% mortality. Treatment of beta 2M-/- mice with anti-asialoGM1 to deplete natural killer cells conferred greater than 70% long-term survival. Compared with wild-type mice, beta 2M-/- mice treated with anti-asialoGM1 produced decreased amounts of proinflammatory cytokines and did not exhibit hypothermia or metabolic acidosis after CLP. Adoptive transfer of CD8+ T and natural killer cells into beta 2M-/- mice treated with anti-asialoGM1 re-established CLP-induced mortality. CD8 knockout mice treated with anti-asialoGM1, which are specifically deficient in CD8+ T and natural killer cells, exhibited 40% long-term survival after CLP. Furthermore, treatment of wild-type mice with antibodies to CD8 and asialoGM1 conferred a significant survival benefit compared with wild-type mice treated with nonspecific IgG. These findings demonstrate that beta 2M-/- mice treated with anti-asialoGM1 are resistant to CLP-induced mortality and that depletion of CD8+ T and natural killer cells largely accounts for the survival benefit observed in these mice.

Topics: Adoptive Transfer; Animals; beta 2-Microglobulin; CD8-Positive T-Lymphocytes; Cecum; Disease Models, Animal; Female; G(M1) Ganglioside; Immunity, Innate; Inflammation; Killer Cells, Natural; Ligation; Lymphopenia; Mice; Mice, Inbred C57BL; Mice, Knockout; Peritonitis; Sepsis; Survival Analysis