S100A12 suppresses pro-inflammatory, but not pro-thrombotic functions of serum amyloid A

Increased Production of Interleukin-10 and Tumor Necrosis Factor-Alpha in Stimulated Peripheral Blood Mononuclear Cells after Inhibition of S100A12

Sepsis may induce immunosuppression and result in death. S100A12 can bind to the receptor for advanced glycation end-products (RAGE) and Toll-like receptor (TLR)4 following induction of various inflammatory responses. It is unclear whether S100A12 significantly influences the immune system, which may be associated with sepsis-related mortality. We measured plasma S100A12 levels and cytokine responses (mean ± standard error mean) of lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) after S100A12 inhibition in healthy controls and patients with sepsis on days one and seven. Day one plasma soluble RAGE (sRAGE) and S100A12 levels in patients with sepsis were significantly higher than those in controls (2481.3 ± 295.0 vs. 1273.0 ± 108.2 pg/mL, p < 0.001; 530.3 ± 18.2 vs. 310.1 ± 28.1 pg/mL, p < 0.001, respectively). Day seven plasma S100A12 levels in non-survivors were significantly higher than those in survivors (593.1 ± 12.7 vs. 499.3 ± 23.8 pg/mL, p = 0.002, respectively). In survivors, plasma sRAGE levels were significantly decreased after 6 days (2297.3 ± 320.3 vs. 1530.1 ± 219.1 pg/mL, p = 0.009, respectively), but not in non-survivors. Inhibiting S100A12 increased the production of tumor necrosis factor (TNF)-α and interleukin (IL)-10 in stimulated PBMCs for both controls and patients. Therefore, S100A12 plays an important role in sepsis pathogenesis. S100A12 may competitively bind to TLR4 and RAGE, resulting in decreased IL-10 and TNF-α production.

Calcium-binding proteins S100A8, S100A9, and S100A12: expression and regulation at the maternal-conceptus Interface in pigs†

Among the many calcium-binding proteins, S100A8, S100A9, and S100A12 play important roles in inflammation, innate immunity, and antimicrobial function, but their expression, regulation, and function at the maternal-conceptus interface in pigs are not fully understood. Therefore, we determined the expression and regulation of S100A8, S100A9, S100A12, and their receptor AGER at the maternal-conceptus interface in pigs. We found that S100A8, S100A9, and S100A12 mRNAs were expressed in the endometrium during the estrous cycle and pregnancy, with the greatest levels on Day (D) 12 of pregnancy, and AGER appeared at greater levels on D15 and D30 of pregnancy than on other days. The expression of S100A8, S100A9, and S100A12 was predominantly localized to epithelial cells in the endometrium, and they were detected in early-stage conceptus and later chorioallantoic tissues during pregnancy. AGER expression was localized to endometrial epithelial and stromal cells and chorionic epithelial cells. In endometrial explant tissues, the expression of S100A8, S100A9, and S100A12 was induced by estrogen, S100A8 by interleukin-1β, and AGER by interferon-γ. We further found that on D12 of pregnancy, the expression of S100A8, S100A9, and S100A12 decreased significantly in the endometria of gilts carrying conceptuses derived from somatic cell nuclear transfer. These results indicate that the expression of S100A8, S100A9, and S100A12 is dynamically regulated in response to conceptus-derived signals at the maternal-conceptus interface, suggesting that S100A8, S100A9, and S100A12 could play a critical role in regulating endometrial epithelial cell function and conceptus implantation to support the establishment and maintenance of pregnancy in pigs.

S100A12 is a promising biomarker in papillary thyroid cancer

S100A12 belongs to the S100 family and acts as a vital regulator in different types of tumors. However, the function of S100A12 in thyroid carcinoma has not yet been investigated. In this study, we analyzed the expression of S100A12 in human papillary thyroid cancer (PTC) samples and two PTC cell lines. In addition, we explored the effects of S100A12 on PTC cell progression in vitro and in vivo. Our results showed that S100A12 was significantly upregulated in PTC specimens. Moreover, silencing S100A12 markedly inhibited PTC cell proliferation, migration, invasion and cell cycle progression. In addition, knockdown of S100A12 significantly reduced the expression of CyclinD1, CDK4 and p-ERK in PTC cells. An in vivo study also showed that silencing S100A12 dramatically suppressed tumor cell growth and decreased Ki67 expression in a xenograft mouse model. This study provides novel evidence that S100A12 serves as an oncogene in PTC. Knockdown of S100A12 suppressed PTC cell proliferation, migration, and invasion and induced G0/G1 phase arrest via the inhibition of the ERK signaling pathway. Therefore, S100A12 may be a potent therapeutic target for PTC.

SAA1 increases NOX4/ROS production to promote LPS-induced inflammation in vascular smooth muscle cells through activating p38MAPK/NF-κB pathway

Background

To investigate the effects of serum amyloid A1 (SAA1) on lipopolysaccharide (LPS) -induced inflammation in vascular smooth muscle cells (VSMCs). SAA1 expression was detected in LPS induced VSMCs at different concentrations for different time by using Western blotting. After pre-incubation with recombinant SAA1 protein, VSMCs were treated with 1 μg/ml LPS for 24 h. The VSMCs were then divided into Control, SAA1 siRNA, Nox4 siRNA, LPS, LPS + SAA1 siRNA, LPS + Nox4 siRNA and LPS + SAA1 siRNA + Nox4 groups. MTT was performed to observe the toxicity of VSMCs. Lucigenin-enhanced chemiluminescence method was used to detect superoxide anion (O₂⁻) production and NADPH oxidase activity. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine expressions of inflammatory factors. Western blotting was used to determine expressions of NOX-4 and p38MAPK/NF-κB pathway related proteins.

Results

LPS promoted SAA1 protein expression in a concentration−/time-dependent manner. Recombinant SAA1 protein could increase NOX4/ROS production and promote the release of inflammatory factors (IL-1β, IL-6, IL-8, IL-17, TNF-α and MCP-1) in LPS (1 μg/ml) - induced VSMCs. Besides, both SAA1 siRNA and NOX-4 siRNA could not only enhance the O₂⁻ production and NADPH oxidase activity, but also up-regulate the protein expression of NOX4, the release of inflammatory factors, and the levels of p-p38 and p-NF-κB p65 in LPS-induced VSMCs. However, no significant differences in each index were observed between LPS group and LPS + SAA1 siRNA + Nox4 group.

Conclusion

SAA1-mediated NOX4/ROS pathway could activate p38MAPK/NF-κB pathway, thereby contributing to the release of inflammatory factors in LPS-induced VSMCs.

Serum amyloid A receptor blockade and incorporation into high-density lipoprotein modulates its pro-inflammatory and pro-thrombotic activities on vascular endothelial cells

The acute phase protein serum amyloid A (SAA), a marker of inflammation, induces expression of pro-inflammatory and pro-thrombotic mediators including ICAM-1, VCAM-1, IL-6, IL-8, MCP-1 and tissue factor (TF) in both monocytes/macrophages and endothelial cells, and induces endothelial dysfunction—a precursor to atherosclerosis. In this study, we determined the effect of pharmacological inhibition of known SAA receptors on pro-inflammatory and pro-thrombotic activities of SAA in human carotid artery endothelial cells (HCtAEC). HCtAEC were pre-treated with inhibitors of formyl peptide receptor-like-1 (FPRL-1), WRW4; receptor for advanced glycation-endproducts (RAGE), (endogenous secretory RAGE; esRAGE) and toll-like receptors-2/4 (TLR2/4) (OxPapC), before stimulation by added SAA. Inhibitor activity was also compared to high-density lipoprotein (HDL), a known inhibitor of SAA-induced effects on endothelial cells. SAA significantly increased gene expression of TF, NFκB and TNF and protein levels of TF and VEGF in HCtAEC. These effects were inhibited to variable extents by WRW4, esRAGE and OxPapC either alone or in combination, suggesting involvement of endothelial cell SAA receptors in pro-atherogenic gene expression. In contrast, HDL consistently showed the greatest inhibitory action, and often abrogated SAA-mediated responses. Increasing HDL levels relative to circulating free SAA may prevent SAA-mediated endothelial dysfunction and ameliorate atherogenesis.

Genome-wide immunity studies in the rabbit: transcriptome variations in peripheral blood mononuclear cells after in vitro stimulation by LPS or PMA-Ionomycin

Background

Our purpose was to obtain genome-wide expression data for the rabbit species on the responses of peripheral blood mononuclear cells (PBMCs) after in vitro stimulation by lipopolysaccharide (LPS) or phorbol myristate acetate (PMA) and ionomycin. This transcriptome profiling was carried out using microarrays enriched with immunity-related genes, and annotated with the most recent data available for the rabbit genome.

Results

The LPS affected 15 to 20 times fewer genes than PMA-Ionomycin after both 4 hours (T4) and 24 hours (T24), of in vitro stimulation, in comparison with mock-stimulated PBMCs. LPS induced an inflammatory response as shown by a significant up-regulation of IL12A and CXCL11 at T4, followed by an increased transcription of IL6, IL1B, IL1A, IL36, IL37, TNF, and CCL4 at T24. Surprisingly, we could not find an up-regulation of IL8 either at T4 or at T24, and detected a down-regulation of DEFB1 and BPI at T24. A concerted up-regulation of SAA1, S100A12 and F3 was found upon stimulation by LPS.

PMA-Ionomycin induced a very early expression of Th1, Th2, Treg, and Th17 responses by PBMCs at T4. The Th1 response increased at T24 as shown by the increase of the transcription of IFNG and by contrast to other cytokines which significantly decreased from T4 to T24 (IL2, IL4, IL10, IL13, IL17A, CD69) by comparison to mock-stimulation. The granulocyte-macrophage colony-stimulating factor (CSF2) was by far the most over-expressed gene at both T4 and T24 by comparison to mock-stimulated cells, confirming a major impact of PMA-Ionomycin on cell growth and proliferation. A significant down-regulation of IL16 was observed at T4 and T24, in agreement with a role of IL16 in PBMC apoptosis.

Conclusions

We report new data on the responses of PBMCs to LPS and PMA-Ionomycin in the rabbit species, thus enlarging the set of mammalian species for which such reports exist. The availability of the rabbit genome assembly together with high throughput genomic tools should pave the way for more intense genomic studies for this species, which is known to be a very relevant biomedical model in immunology and physiology.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1218-9) contains supplementary material, which is available to authorized users.

Chronic sustained inflammation links to left ventricular hypertrophy and aortic valve sclerosis: a new link between S100/RAGE and FGF23

BACKGROUND

Cardiovascular disease including left ventricular hypertrophy, diastolic dysfunction and ectopic valvular calcification are common in patients with chronic kidney disease (CKD). Both S100A12 and fibroblast growth factor 23 (FGF23) have been identified as biomarkers of cardiovascular morbidity and mortality in patients with CKD. We tested the hypothesis that human S100/calgranulin would accelerate cardiovascular disease in mice subjected to CKD.

METHODS

This review paper focuses on S100 proteins and their receptor for advanced glycation end products (RAGE) and summarizes recent findings obtained in novel developed transgenic hBAC-S100 mice that express S100A12 and S100A8/9 proteins. A bacterial artificial chromosome of the human S100/calgranulin gene cluster containing the genes and regulatory elements for S100A8, S100A9 and S100A12 was expressed in C57BL/6J mice (hBAC-S100). CKD was induced by ureteral ligation, and hBAC-S100 mice and WT mice were studied after 10 weeks of chronic uremia.

RESULTS

hBAC-S100 mice with CKD showed increased FGF23 in the heart, left ventricular hypertrophy (LVH), diastolic dysfunction, focal cartilaginous metaplasia and calcification of the mitral and aortic valve annulus together with aortic valve sclerosis. This phenotype was not observed in WT mice with CKD or in hBAC-S100 mice lacking RAGE with CKD, suggesting that the inflammatory milieu mediated by S100/RAGE promotes pathological cardiac hypertrophy in CKD. In vitro, inflammatory stimuli including IL-6, TNFα, LPS, or serum from hBAC-S100 mice up regulated FGF23 mRNA and protein in primary murine neonatal and adult cardiac fibroblasts.

CONCLUSIONS

Taken together, our study shows that myeloid-derived human S100/calgranulin is associated with the development of cardiac hypertrophy and ectopic cardiac calcification in a RAGE dependent manner in a mouse model of CKD. We speculate that FGF23 produced by cardiac fibroblasts in response to cytokines may act in a paracrine manner to accelerate LVH and diastolic dysfunction in hBAC-S100 mice with CKD. We suggest that S100/RAGE-mediated chronic sustained systemic inflammation is linked to pathological cardiac remodeling via direct up regulation of FGF23 in cardiac fibroblasts, thereby providing a new mechanistic understanding for the common association between CKD, diabetes, metabolic syndrome, or hypertension with left ventricular hypertrophy with diastolic dysfunction.

Calgranulins may contribute vascular protection in atherogenesis

S100A8, S100A9 and S100A12 are considered proinflammatory mediators of atherosclerosis. Known as calgranulins, they are major components of neutrophils and are upregulated in macrophages and foam cells. They influence leukocyte recruitment, and may propagate inflammation by binding TLR4 and/or receptor for advanced glycation endproducts (RAGE). However, the receptors for calgranulins remain an enigma; we have no evidence for TLR4 or RAGE activation by S100A8 or S100A12. Moreover, gene regulation studies suggest antiinflammatory functions for S100A8 and emerging reports indicate pleiotropic roles. Unlike S100A9, S100A8 effectively scavenges oxidants generated by the myeloperoxidase system in vivo, forming novel thiol modifications. S100A8 is also readily S-nitrosylated, stabilizing nitric oxide and transporting it to hemoglobin. S100A8-SNO reduces leukocyte transmigration in the vasculature. S-glutathionylation of S100A9 modifies its effects on leukocyte adhesion. Both S100A8 forms inhibit mast cell activation, at least partially by scavenging reactive oxygen species required for signaling. Conversely, S100A12 activates and sequesters mast cells. However S100A12 suppresses proinflammatory cytokine induction by SAA-activated monocytes and macrophages, and inhibits matrix metalloprotease activity. We propose that the abundance and types of cells expressing calgranulins in particular microenvironments, their relative concentrations and post-translational modifications may have distinct functional outcomes, including those that are protective, at different stages of atherogenesis.