Lary nel abao nc-nga mice revised report
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Lary nel abao nc-nga mice revised report

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Report on the susceptibility of mice to Listeria Monocytogenes

Report on the susceptibility of mice to Listeria Monocytogenes

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Lary nel abao nc-nga mice revised report Lary nel abao nc-nga mice revised report Document Transcript

  • アバオラリーネルビルバオ February 26, 2010 Infection Immunology 川本先生 Why is NC/Nga Mice Highly-Susceptible to LM Infection In the lecture that was presented on the Function of Immune Responses Against Infection last January 27, 2010, we were asked about our hypothesis on the role of Interleukin (IL)-10 in Listeriosis. Before I discussed the figures given, I would like to define some important terms of the report. According to Wikipedia, Listeria monocytogenes (LM) is a facultative intracellular bacterium that is the causative agent of Listeriosis. It is one of the most virulent food borne pathogens with twenty (20) to thirty (30) percent of clinical infections resulting in death. Responsible for approximately 2,500 illnesses and 500 deaths in the United States (U.S.) annually, listeriosis is the leading cause of death among food borne bacterial pathogens with fatality rates exceeding even Salmonella and Clostridium botulinum. LM is a Gram-positive bacterium, in the division Firmicutes, named for Joseph Lister. Motile via flagella at 30 °C and below but usually not at 37 °C, LM can instead move within eukaryotic cells by explosive polymerization of actin filaments (known as comet tails or actin rockets). Studies suggest that up to 10% of human gastrointestinal tracts may be colonized by LM.1 Nevertheless, clinical diseases due to LM are more frequently recognized by veterinarians, especially as meningo- encephalitis in ruminants. More recently, LM has been used as the model organism to illustrate the patho-biotechnology concept. Meanwhile, Wikipedia defined Interferon-gamma (IFN-γ) as a dimerized soluble cytokine that is the only member of the type II class of interferons. This interferon was originally called macrophage-activating factor, a term now used to describe a larger family of proteins to which IFN-γ belongs. IFN-γ, or type II interferon, functions as a cytokine that is critical for innate and adaptive immunity against viral and intracellular bacterial infections and for tumor control. Aberrant IFN-γ expression is associated with a number of auto inflammatory and autoimmune diseases. The importance of IFN-γ in the immune system stems in part from its ability to inhibit viral replication directly, but, most important, derives from its immunostimulatory and immunomodulatory effects. IFN-γ is produced predominantly by natural killer (NK) and natural killer T (NKT) cells as part of the innate immune response, and by CD4 and CD8 cytotoxic T lymphocyte (CTL) effector T cells once antigen-specific immunity develops. And lastly, Interleukin-10 (IL-10), also known as human cytokine synthesis inhibitory factor (CSIF), is known as an anti-inflammatory cytokine. This cytokine is produced primarily by monocytes and to a lesser extent by lymphocytes. This cytokine has pleiotropic effects in immunoregulation and inflammation. It down-regulates the expression of Th1 cytokines, MHC class II antigens, and costimulatory molecules on macrophages. It also enhances B cell survival, proliferation, and antibody production. 1 Ramaswamy, Vidhya and Cresence, Vincent Mary. "Listeria - Review of Epidemiology and Pathogenesis." J Microbiol Immunol Infect. (2007). 40:4-13 1
  • This cytokine can block NF-κB activity, and is involved in the regulation of the JAK- STAT signaling pathway. Knockout studies in mice suggested the function of this cytokine as an essential immunoregulator in the intestinal tract.2 A study in mice has shown that interleukin-10 is also produced by mast cells, counteracting the inflammatory effect that these cells have at the site of an allergic reaction.3 It is capable of inhibiting synthesis of pro-inflammatory cytokines like IFN- γ, IL-2, IL-3, TNFα and GM-CSF made by cells such as macrophages and the Type 1 T helper cells. IL-10 also displays potent abilities to suppress the antigen presentation capacity of antigen presenting cells. However, it is also stimulatory towards certain T cells, mast cells and stimulates B cell maturation and antibody production. In Figure 1, a dose of LM 8.0 x 105 was administered per head to the NC/Nga, BALB/ c, and C57BL/6 mice. It can be seen that until day 3 post infection, the three (3) mice have a survival rate of 100%. However, by day 4 post infection, the survival rate of the NC/Nga mice went down to around 10%. And finally, by day 5 post infection, there were no more survivors in the NC/Nga mice (unlike in the BALB/c mice and C57BL/6 mice). In the day 5 post infection, BALB/c mice had a survival rate of 80% while C57BL/6 mice, 100%. Figure 1. NC/Nga Mice is Highly Susceptible to LM Infection 2 "Entrez Gene: IL10 interleukin 10" 3 Grimbaldeston, MA, et. al. (October 2007). "Mast cell-derived interleukin 10 limits skin pathology in contact dermatitis and chronic irradiation with ultraviolet B". Nat. Immunol. 8 (10): 1095–104. 2
  • In the case of Figure 2, the IFN-γ level in NC/Nga mice increased to around 13,000 during the day 1 post infection. However, it decreased to around 12,000 during the day 2 post infection. And finally, it further decreased to 11,000 during the day 3 post infection. After day 3 post infection, there was no more data on IFN-γ as the NC/Nga Mice have died. This may lead to a hypothesis that the IFN-γ is important to the survival rate of NC/Nga Mice being subjected to Listeriosis. The analysis for the role of IL-10 is the opposite of that of the IFN-γ. The serum level of IL-10 for NC/Nga mice is at 500 during the day 1 post infection. It increased to around 600 serum levels during the day 2 post infection. Then, it shot up to the 3,000 level by day 3 post infection. However, by day 4 post infection, all the NC/Nga mice have died. It seems that the presence of significantly high serum levels of IL-10 is detrimental to the survival rate of NC/Nga mice. Figure 2. Increased serum levels of IL-10 in NC/Nga Mice The results of IL-10 in Figure 1 are consistent with the results of a similar study on the Role of IL-10 in a Neonatal Mouse Listeriosis Model that was done in 1999. This study was undertaken to test the hypothesis that altered IL-10 production plays a role in the increased susceptibility of neonates to listeriosis. 4 Plasma IL-10 levels were measured in neonatal and adult mice at various times after infection with Listeria monocytogenes. Collectively, the data of the study suggested that an overproduction of IL-10 by macrophages may at least partially explain the increased susceptibility of neonates to listeriosis (and provide further evidence that cytokine production is different in adults and neonates). The conclusion of the study was that neonatal mice produce high IL-10 levels during listeriosis or after the injection of killed bacteria. Overproduction of the cytokine is apparently detrimental during listeriosis, but may be beneficial in infections by other pathogens. 4 Francesco Genovese, et. al., Role of IL-10 in a Neonatal Mouse Listeriosis Model, The Journal of Immunology, 1999, 163, 2777-2782. 3
  • Meanwhile, according to another study, high doses of Listeria monocytogenes overcome the ability of a normal mouse to control the infection, due to massive bacterial replication. Treatment with an anti-interleukin 10 (IL-10) receptor monoclonal antibody prevented the fatal course of infection with high doses of bacteria. This work showed that blocking the receptor for IL-10 may have useful therapeutic applications.5 In Figure 3 on the next page, it can be seen that an Anti-IL-10 was administered to the NC/Nga mice to see its effects. In this scenario, an LM of 7.4 x 104 per head was administered. The result of this figure is not conclusive. It is also inconsistent with Figure 2. In fact, the decreased serum levels of the IL-10 led to a 0% survival rate by day 4 post infection (shown by the red line). In the case of the control group (the blue line), survival of the NC/Nga mice remained steady at 40% from day 6 to day 14 post infection because of the presence of IL-10. Figure 3. Effects of the Anti-IL-10 Dosage to NC/Nga Mice In the case of Figure 4 (on the next page), the administration of the IL-10 to the three types of mice (i.e. NC/Nga, BALB/c, and C57BL/6J) led to their increased survival rates. In this model, an LM of 4.2 x 105 per head was administered. In the case of BALB/c and C57BL/6J mice, survival rates increased to 100%. This happened at day 3 post infection for BALB/c mice while for C57BL/6J, at day 5 post infection. The result of Figure 4 is also inconsistent with the result of Figure 2. 5 Regina A. Silva and Rui Appelberg, Blocking the Receptor for Interleukin 10 Protects Mice from Lethal Listeriosis, 2001, American Society for Microbiology 4
  • Figure 4. Effects of IL-10 Dosage to NC/Nga, BALB/c, and C57BL/6J Mice The role of IL-10 in listeriosis is not entirely clear. Anti-IL-10 treatment resulted in increased bacterial replication and lethality late in the course of infection, after producing an early improvement in another study.6 In another report, however, adult IL-10-deficient mice showed increased resistance to L. monocytogenes,7 while administration of r IL-10 severely decreased innate defenses against the organism.8 Based on Figure 2 alone, the conclusion would be that the presence of IFN-γ increased the resistance of the NC/Nga mice against listeriosis. On the other hand, significantly high levels of IL-10 made the NC/Nga mice highly-susceptible to Listeriosis. The results of the other figures above (Figures 3-4) did not show conclusive evidence on the Figure 2 hypothesis. In this regard, additional studies should be carried out to further understand the real role of IL-10 in listeriosis. 6 25. Wagner, R. D., N. M. Maroushek, J. F. Brown, and C. J. Czuprynski, 1994, Treatment with anti-interleukin-10 monoclonal antibody enhances early resistance to but impairs complete clearance of Listeria monocytogenes infection in mice, Infection Immunology, 62:2345. 7 26. Day, W., G. Ko¨hler, and F. Brombacher,1997, Both innate and acquired immunity to Listeria monocytogenes infection are increased in IL-10-deficient mice, Journal of Immunology, 158:2259. 8 27. Kelly, J. P., and G. J. Bancroft, 1996, Administration of interleukin-10 abolishes innate resistance to Listeria monocytogenes, European Journal of Immunology, 26:356. 5