Lipopolysaccharide, CD14 and Toll-like receptors: an emerging link between innate immunity and atherosclerotic disease

Punicalagin protects bovine endometrial epithelial cells against lipopolysaccharide-induced inflammatory injury

OBJECTIVE

Bovine endometritis is one of the most common reproductive disorders in cattle. The aim of this study was to investigate the anti-inflammation potential of punicalagin in lipopolysaccharide (LPS)-induced bovine endometrial epithelial cells (bEECs) and to uncover the underlying mechanisms.

METHODS

bEECs were stimulated with different concentrations (1, 10, 30, 50, and 100 μg/ml) of LPS for 3, 6, 9, 12, and 18 h. MTT assay was used to assess cell viability and to identify the conditions for inflammatory injury and effective concentrations of punicalagin. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to assess gene expression of pro-inflammatory cytokines. Western blotting was used to assess levels of inflammation-related proteins.

RESULTS

Treatment of bEECs with 30 µg/ml LPS for 12 h induced cell injury and reduced cell viability. Punicalagin (5, 10, or 20 µg/ml) pretreatment significantly decreased LPS-induced productions of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α (TNF-α) in bEECs. Molecular research showed that punicalagin inhibited the activation of the upstream mediator nuclear factor-κB (NF-κB) by suppressing the production of inhibitor κBα (IκBα) and phosphorylation of p65. Results also indicated that punicalagin can suppress the phosphorylation of mitogen-activated protein kinases (MAPKs) including p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK).

CONCLUSIONS

Punicalagin may attenuate LPS-induced inflammatory injury and provide a potential option for the treatment of dairy cows with Escherichia coli endometritis.

Immune system and atherosclerotic disease: heterogeneity of leukocyte subsets participating in the pathogenesis of atherosclerosis

Atherosclerosis is an inflammatory disease in which a systemic inflammatory reaction is combined with an accumulation of immune cells, such as monocytes/macrophages, dendritic cells (DCs), and numerous lymphocytes, in atherosclerotic plaques. The immune system, comprising innate immunity and adaptive immunity, has been implicated in all stages of atherosclerosis, from initiation through progression and in atherothrombotic complications. It is clear that different subpopulations of leukocytes are involved in the pathogenesis of atherosclerosis and plaque instability. Recent studies have also demonstrated that each heterogeneity of immune-associated cells contributes to the atherogenic and atheroprotective axis. This review highlights recent advances in research and explores the role of the complex heterogeneity of leukocyte subsets, especially monocytes/macrophages (inflammatory monocytes, resident monocytes, M1, and M2), DCs (myeloid DCs, plasmacytoid DCs, pre DCs, conventional DCs, inflammatory DCs), and CD4(+) cells (T-helper 1, T-helper 2, regulatory T, and T-helper 17 cells), in the initiation and development of atherosclerotic disease and its complications.