Search

Sepsis remains one of the most lethal and costly conditions treated in U.S. hospitals, with approximately 50% of cases caused by Gram-negative bacterial infections. Septic shock is induced when lipopolysaccharide (LPS), the main component of Gram-negative outer bacterial membrane, signals through the Toll-like receptor 4 (TLR4) complex. Lethal endotoxemia, a model for septic shock, was induced in WT C57BL6 and TLR4–/–mice by administration of Escherichia coliLPS. WT LPS treated mice showed high morbidity, while PBS treated LPS and treated TLR4–/–mice did not. ANOVA analysis of label-free quantification of longitudinal serum proteome revealed 182 out of 324 proteins in LPS injected WT mice that were significantly changed across four time points (0, 6, 12, and 18 h). No significant changes were identified in the two control groups. From the 182 identified proteins, examples of known sepsis biomarkers were validated by ELISA, which showed similar trends as MS proteomics data. Longitudinal analysis within individual mice produced 3-fold more significantly changed proteins than pair-wise comparison. A subsequent global analysis of WT and TLR4–/–mice identified pathways activated independent of TLR4. These pathways represent possible compensatory mechanisms that allow for control of Gram-negative bacterial infection regardless of host immune status.

UV irradiation-induced cellular damage is classically associated with apoptosis and is known to result in systemic immunosuppression. How the decision to undergo apoptosis is made following UV is not fully understood. We hypothesize that a central mediator of TLR signaling, MyD88, determines cell fate after UV exposure. Survival after UV of immortalized bone marrow-derived macrophages (BMDM) and ex vivo peritoneal macrophages (PM) from MyD88 germline-deficient mice (MyD88-/-) was significantly higher than wild type (WT) PM. UV-induced apoptosis (DNA laddering) in PM and epidermis of MyD88-/-animals versus WT was decreased. In MyD88-/-PM, decreased cleavage of caspase 3, as well as pro-necroptotic protein, RIP1, and a significant increase in transcription and release of pro-inflammatory TNF-α, suggest that necroptosis, rather than apoptosis, has been initiated. In vivo studies confirm this hypothesis after UV, showing low apoptosis by TUNEL and inflammation in MyD88-/-skin sections. Considering that MyD88 participates in many TLR pathways, BMDM from TLR2-/-, TLR4-/-and WT mice were compared for evidence of UV-induced apoptosis. Only TLR4-/-BMDM and PM had a similar phenotype to MyD88-/-, suggesting that the TLR4–MyD88 axis importantly contributes to cell fate decision. Our study describes a new cellular consequence of MyD88 signaling after UV, and may provide rationale for therapies to mitigate UV-induced immunosuppression.

Manganese chloride (MnCl2) 2.5 is included in the extended metals patch test series to evaluate patients for contact hypersensitivity to this metal salt.

Infectious diseases propagated by arthropod vectors, such as tularemia, are commonly initiated via dermal infection of the skin. However, due to the technical difficulties in achieving accurate and reproducible dermal deposition, intradermal models are less commonly used.

ABSTRACTAdjuvant properties of bacterial cell wall components like MPLA (monophosphoryl lipid A) are well described and have gained FDA approval for use in vaccines such as Cervarix. MPLA is the product of chemically modified lipooligosaccharide (LOS), altered to diminish toxic proinflammatory effects while retaining adequate immunogenicity. Despite the virtually unlimited number of potential sources among bacterial strains, the number of useable compounds within this promising class of adjuvants are few. We have developed bacterial enzymatic combinatorial chemistry (BECC) as a method to generate rationally designed, functionally diverse lipid A. BECC removes endogenous or introduces exogenous lipid A-modifying enzymes to bacteria, effectively reprogramming the lipid A biosynthetic pathway. In this study, BECC is applied within an avirulent strain of Yersinia pestisto develop structurally distinct LOS molecules that elicit differential Toll-like receptor 4 (TLR4) activation. Using reporter cell lines that measure NF-κB activation, BECC-derived molecules were screened for the ability to induce a lower proinflammatory response than Escherichia coliLOS. Their structures exhibit varied, dose-dependent, TLR4-driven NF-κB activation with both human and mouse TLR4 complexes. Additional cytokine secretion screening identified molecules that induce levels of tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) comparable to the levels induced by phosphorylated hexa-acyl disaccharide (PHAD). The lead candidates demonstrated potent immunostimulation in mouse splenocytes, human primary blood mononuclear cells (PBMCs), and human monocyte-derived dendritic cells (DCs). This newly described system allows directed programming of lipid A synthesis and has the potential to generate a diverse array of TLR4 agonist candidates.IMPORTANCEThere is an urgent need to develop effective vaccines against infectious diseases that continue to be major causes of morbidity and mortality worldwide. Making effective vaccines requires selecting an adjuvant to strengthen an appropriate and protective immune response. This work describes a practical method, bacterial enzymatic combinatorial chemistry (BECC), for generating functionally diverse molecules for adjuvant use. These molecules were analyzed in cell culture for their ability to initiate immune stimulatory activity. Several of the assays described herein show promising in vitrocytokine production and costimulatory molecule expression results, suggesting that the BECC molecules may be useful in future vaccine preparations.