Cell Activation of Human Macrophages by Lipoteichoic Acid Is Strongly Attenuated by Lipopolysaccharide-binding Protein

The Microbiome-TIME Axis: A Host of Possibilities

Cancer continues to be a significant source of mortality and morbidity worldwide despite progress in cancer prevention, early detection, and treatment. Fortunately, immunotherapy has been a breakthrough in the treatment of many cancers. However, the response to immunotherapy treatment and the experience of associated side effects varies significantly between patients. Recently, attention has been given to understanding the role of the tumor immune microenvironment (TIME) in the development, progression, and treatment response of cancer. A new understanding of the role of the microbiota in the modulation of the TIME has further complicated the story but also unlocked a new area of adjuvant therapeutic research. The complex balance of tumor-permissive and tumor-suppressive immune environments requires further elucidation in order to be harnessed as a therapeutic target. Because both the TIME and the microbiome show importance in these areas, we propose here the concept of the "microbiome-TIME axis" to review the current field of research and future directions.

Gram-positive bacteria cell wall-derived lipoteichoic acid induces inflammatory alveolar bone loss through prostaglandin E production in osteoblasts

Periodontitis is an inflammatory disease associated with severe alveolar bone loss and is dominantly induced by lipopolysaccharide from Gram-negative bacteria; however, the role of Gram-positive bacteria in periodontal bone resorption remains unclear. In this study, we examined the effects of lipoteichoic acid (LTA), a major cell-wall factor of Gram-positive bacteria, on the progression of inflammatory alveolar bone loss in a model of periodontitis. In coculture of mouse primary osteoblasts and bone marrow cells, LTA induced osteoclast differentiation in a dose-dependent manner. LTA enhanced the production of PGE₂ accompanying the upregulation of the mRNA expression of mPGES-1, COX-2 and RANKL in osteoblasts. The addition of indomethacin effectively blocked the LTA-induced osteoclast differentiation by suppressing the production of PGE₂. Using ex vivo organ cultures of mouse alveolar bone, we found that LTA induced alveolar bone resorption and that this was suppressed by indomethacin. In an experimental model of periodontitis, LTA was locally injected into the mouse lower gingiva, and we clearly detected alveolar bone destruction using 3D-μCT. We herein demonstrate a new concept indicating that Gram-positive bacteria in addition to Gram-negative bacteria are associated with the progression of periodontal bone loss.

Early host response in the mammary gland after experimental Streptococcus uberis challenge in heifers

Streptococcus uberis is a highly prevalent causative agent of bovine mastitis, which leads to large economic losses in the dairy industry. The aim of this study was to examine the host response during acute inflammation after experimental challenge with capsulated Strep. uberis. Gene expression in response to Strep. uberis was compared between infected and control quarters in 3 animals. All quarters (n=16) were sampled at 16 different locations. Microarray data showed that 239 genes were differentially expressed between infected and control quarters. No differences in gene expression were observed between the different locations. Microarray data were confirmed for several genes using quantitative PCR analysis. Genes differentially expressed due to early Strep. uberis mastitis represented several stages of the process of infection: (1) pathogen recognition; (2) chemoattraction of neutrophils; (3) tissue repair mechanisms; and (4) bactericidal activity. Three different pathogen recognition genes were induced: ficolins, lipopolysaccharide binding protein, and toll-like receptor 2. Calgranulins were found to be the most strongly upregulated genes during early inflammation. By histology and immunohistochemistry, we demonstrated that changes in gene expression in response to Strep. uberis were induced both in infiltrating somatic milk cells and in mammary epithelial cells, demonstrating that the latter cell type plays a role in milk production as well as immune responsiveness. Given the rapid development of inflammation or mastitis after infection, early diagnosis of (Strep. uberis) mastitis is required for prevention of disease and spread of the pathogen. Insight into host responses could help to design immunomodulatory therapies to dampen inflammation after (early) diagnosis of Strep. uberis mastitis. Future research should focus on development of these early diagnostics and immunomodulatory components for mastitis treatment.

A functional variant of lipopolysaccharide binding protein predisposes to sepsis and organ dysfunction in patients with major trauma

OBJECTIVE

To determine the hypothesis that genetic variations of the lipopolysaccharide-binding protein (LBP) gene influence risk for the development of sepsis and multiple organ dysfunction (MOD) in patients with major trauma.

BACKGROUND

Lipopolysaccharide-binding protein plays a central role in innate immune response as the first line of defense and directing the microbial-induced activation of the inflammatory host response. Although a total of 112 single nucleotide polymorphisms (SNPs) have been identified so far within the entire LBP gene, only a few SNPs have been studied.

METHODS

Nine haplotype tagging SNPs (htSNPs) were selected from 51 SNPs with a minor allele frequency of ≥5% using the HapMap database for the Chinese Han population. Two independent cohorts of major trauma patients were recruited. The 9 htSNPs were genotyped using pyrosequencing method and analyzed in relation to the risk of development of sepsis and MOD, LBP production, and lipopolysaccharide (LPS)-induced activation of peripheral blood leukocytes. Moreover, the functionality of the rs2232618 polymorphism was assessed by the observation of its effects on the binding and activation of LPS and the LBP-CD14 interaction.

RESULTS

Among the 9 htSNPs, only the rs2232618 was significantly associated with higher susceptibility to sepsis and MOD in the 2 independent cohorts of major trauma patients recruited from southwest and eastern China. This SNP was also significantly associated with LPS-induced activation of peripheral blood leukocytes. In addition, the rs2232618 polymorphism could enhance LBP protein activities, showing significant increases in LPS binding to macrophages, LPS-induced cellular activation, and LBP-CD14 interaction at the presence of the variant LBP protein.

CONCLUSIONS

The rs2232618 polymorphism is a functional SNP and confers host susceptibility to sepsis and multiple organ dysfunction in patients with major trauma.