The role of HMGB1 during Listeria Infection.

Abstract Listeria Monocytogenes (LM) is a gram-positive, intracellular foodborne pathogen which can cause severe disease in immunocompromised individuals and is a leading cause of death from foodborne infections. LM stimulates the immune system via pathogen-associated molecular patterns (PAMPs) such as lipoproteins which interact with pattern recognition receptors (PRRs) including toll-like receptors (TLR2). These interactions induce activation of immune cells resulting in the production of cytokines such as TNFa, IL-1 and IL-6. PRRs also induce immune activity in response to damage-associated molecular patterns (DAMPs) which are released from host cells in response to cellular damage. High Mobility Group Box 1 (HMGB1) protein is a DAMP that has been shown to be actively secreted from macrophages during sterile inflammation resulting in the production of TNFa by binding to toll-like receptor 4 (TLR4). Even though HMGB1 has been shown to be an active player during sterile inflammation, nothing has been published about its function during immune responses to any pathogenic infection. b. Purpose The purpose of our study is to understand the effect LM infection has on transcription, translation and post translational modification of HMGB1. We are also studying the effect of HMGB1 on inflammatory cytokines such as TNFa, IL-1 and IL-6, neutrophil recruitment to infected organs, and bacterial burden during LM infection. c. Methods C57BL/6 mice were infected with LM and at 3 days post infection immune cells were isolated from the spleen and bone marrow. The cells were used for rt-PCR to study HMGB1 transcription, and western blotting to study the translation of HMGB1. The aforementioned cells were also incubated overnight with 10ng/mL of HMGB1, and supernatants were harvested to measure TNFa by ELISA. d. Results Our results indicate that LM does not have a significant effect on HMGB1 transcription and translation in the spleen and bone marrow. We also show that at 10ng/mL, HMGB1 does not enhance TNFa production in spleen and bone marrow cells. e. Conclusion Our results indicate that HMGB1 production is not influenced by LM infection. Furthermore, our data suggest that HMGB1 may not influence immune responses against LM in vitro. Further studies are required to elucidate the in vivo functions of HMGB1 during LM infection. b. Purpose The purpose of our study is to understand the effect LM infection has on transcription, translation and post translational modification of HMGB1. We are also studying the effect of HMGB1 on inflammatory cytokines such as TNFa, IL-1 and IL-6, neutrophil recruitment to infected organs, and bacterial burden during LM infection. c. Methods C57BL/6 mice were infected with LM and at 3 days post infection immune cells were isolated from the spleen and bone marrow. The cells were used for rt-PCR to study HMGB1 transcription, and western blotting to study the translation of HMGB1. The aforementioned cells were also incubated overnight with 10ng/mL of HMGB1, and supernatants were harvested to measure TNFa by ELISA. d. Results Our results indicate that LM does not have a significant effect on HMGB1 transcription and translation in the spleen and bone marrow. We also show that at 10ng/mL, HMGB1 does not enhance TNFa production in spleen and bone marrow cells. e. Conclusion Our results indicate that HMGB1 production is not influenced by LM infection. Furthermore, our data suggest that HMGB1 may not influence immune responses against LM in vitro. Further studies are required to elucidate the in vivo functions of HMGB1 during LM infection.