Induced B7-H1 expression on human renal tubular epithelial cells by the sublytic terminal complement complex C5b-9

Porphyromonas gingivalis induced up-regulation of PD-L1 in colon carcinoma cells

Programmed death-ligand-1 (PD-L1) is a ligand for programmed death receptor (PD-1) that plays a major role in cell-mediated immune response; it regulates T-cell activation and regulates survival and functions of activated T cells. Expression of PD-L1 can induce chronic inflammation and activate mechanisms of immune evasion. PD-L1 is expressed in most of human carcinomas. Porphyromonas gingivalis (P. gingivalis) is a major keystone pathogen in periodontitis that invade host cells and disposes a variety of virulence factors. The aim of the present study was to clarify the signaling pathway of P. gingivalis molecules that induce PD-L1 up-regulation in colon carcinoma cells. Additionally, it was investigated which components of P. gingivalis are responsible for PD-L1 induction. Colon cancer cells (CL-11) were stimulated with total membrane (TM) fractions, peptidoglycans (PDGs) and viable P. gingivalis bacteria. Seven signaling molecule inhibitors were used: receptor-interacting serine/threonine-protein kinase 2 (RIP2) tyrosine kinase inhibitor, nucleotide-binding oligomerization domain (NOD)-like receptor 1&2 inhibitor, NOD-like receptor, nuclear factor kappa B inhibitor, c-Jun N-terminal kinases inhibitor, mitogen-activated protein/extracellular signal-regulated kinase inhibitor, mitogen activated kinase (MAPK) inhibitor. PD-L1 protein expression was examined by western blot analysis and quantitative real time PCR. It was demonstrated that the TM fraction and PDG induced up-regulation of PD-L1 expression in colon cancer cells. In conclusion, the results of this study suggest that PDG of P. gingivalis plays a major role in PD-L1 up-regulation in colon cancer cells. In addition, the mechanism of PD-L1 up-regulation depends on NOD 1 and NOD 2 and involves activation of RIP2 and MAPK signaling pathways.

Serum proteins associated with periodontitis relapse post-surgery: A pilot study

BACKGROUND

The knowledge of which genes and proteins that are connected to the susceptibility to gingivitis with subsequent local tissue degradation seen in periodontitis is insufficient. Changes of serum proteins associated with recurrence of bleeding on probing (BOP) and increased periodontal pocket depths (PPD) after surgical treatment of periodontitis could reveal molecules that could be early signals of tissue destruction and/or of importance for systemic effects in other tissues or organs.

METHODS

We performed a longitudinal pilot study and followed 96 inflammation-related proteins over time in serum from patients who underwent surgical treatment of periodontitis (n= 21). The samples were taken before (time 0), and then at 3, 6, and 12 months after surgery. Changes in protein levels were analysed in relation to the clinical outcome measures, that is, proportion of surfaces affected by BOP and PPD.

RESULTS

Changes in treatment outcomes with early signs of relapse in periodontitis after surgical treatment, for example, increased BOP and PPDs, were during 12-months follow up associated with increased serum levels of high-sensitivity C-reactive protein (hs-CRP) and programmed death-ligand 1 (PD-L1), and reduced serum levels of cystatin-D protein.

CONCLUSION

This study shows that clinical signs of recurrence of periodontitis after surgery are reflected in serum, but larger studies are needed for verification. Our novel findings of an association between increased PD-L1- and decreased cystatin D-levels and recurrence in periodontitis are interesting because PD-L1 has been shown to facilitate bacterial infections and chronic inflammation and cystatin D to inhibit tissue destruction. Our results justify mechanistic studies regarding the role of these molecules in periodontitis.

Porphyromonas gingivalis Cell Wall Components Induce Programmed Death Ligand 1 (PD-L1) Expression on Human Oral Carcinoma Cells by a Receptor-Interacting Protein Kinase 2 (RIP2)-Dependent Mechanism

Programmed death-ligand 1 (PD-L1/B7-H1) serves as a cosignaling molecule in cell-mediated immune responses and contributes to chronicity of inflammation and the escape of tumor cells from immunosurveillance. Here, we investigated the molecular mechanisms leading to PD-L1 upregulation in human oral carcinoma cells and in primary human gingival keratinocytes in response to infection with Porphyromonas gingivalis (P. gingivalis), a keystone pathogen for the development of periodontitis. The bacterial cell wall component peptidoglycan uses bacterial outer membrane vesicles to be taken up by cells. Internalized peptidoglycan triggers cytosolic receptors to induce PD-L1 expression in a myeloid differentiation primary response 88 (Myd88)-independent and receptor-interacting serine/threonine-protein kinase 2 (RIP2)-dependent fashion. Interference with the kinase activity of RIP2 or mitogen-activated protein (MAP) kinases interferes with inducible PD-L1 expression.

The role of programed death-ligand 1 in renal diseases

Programed death-ligand 1 (PD-L1, B7-H1, CD274) is a coinhibitory molecule that plays a vital role in the pathogenesis of both neoplastic and nonneoplastic diseases. However, the role of PD-L1 in primary and secondary renal diseases remains to be clarified. Previous studies have shown that both intracellular and intercellular PD-L1 participate in renal diseases via complex mechanisms. PD-L1 plays a dual role in lupus nephritis and has a protective effect in renal ischemia reperfusion injury and nephrotoxic nephritis but not in proliferative immune complex glomerulonephritis. PD-L1 supplementation, anti-PD-L1 antibodies, and D-peptide antagonists have promising application prospects in the treatment of renal diseases. In this review, we summarize the available data published on PD-L1 in renal diseases for the first time.

M1 Macrophages Induce PD-L1 Expression in Hepatocellular Carcinoma Cells Through IL-1β Signaling

Hepatocellular carcinoma (HCC) is a prototype of inflammation-related cancer, harboring M1-like and M2-like tumor-associated macrophages. M1 macrophages are thought to be tumoricidal, but some studies report its pro-tumor role. The programmed cell death-ligand (PD-L) 1 expressed in HCC cells is a critical checkpoint molecule to mediate immune escape of HCC. The PD-L1 expression in HCC cells is inducible. In the present study, we ask whether M1 macrophages induce the expression of PD-L1 in HCC cells. First, an association between M1 macrophage infiltration and PD-L1 expression in HCC tissues was determined by bioinformatics and immunohistochemistry experiments. The enrichment score of M1 macrophages was correlated to PD-L1 expression in 90 HCC samples from GEO database. Besides, infiltration of CD68+HLA-DR+ M1-like macrophages correlated with PD-L1 expression level in HCC cells. Moreover, M1-conditioned media was prepared from M1 macrophages derived from THP-1 cell, RAW264.7 cell or murine bone marrow. These supernatants induced expression of PD-L1 in HCC cells. Furthermore, inflammatory cytokine IL-1β in the supernatants was identified to account for the inducible PD-L1 expression by siRNA assay and receptor blockade assay. Additionally, transcription factor p65 and IRF1 in the HCC cells were revealed by CHIP assay to mediate the inducible PD-L1 expression. All the results demonstrate that M1 macrophages induced expression of PD-L1 in HCC cells, supporting the pro-tumor role of M1 macrophages.

NF-κB signaling pathway-enhanced complement activation mediates renal injury in trichloroethylene-sensitized mice

Both NF-κB pathway and complement activation appear to be involved in kidney damage induced by trichloroethylene (TCE). However, any relationship between these two systems has not yet been established. The present study aimed to clarify the role of NF-κB in complement activation and renal injury in TCE-sensitized BALB/c mice. Mice were sensitized by an initial subcutaneous injection and repeated focal applications of TCE to dorsal skin at specified timepoints. NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) was injected (intraperitoneal) before the final two focal TCE challenges. In the experiments, mice had their blood and kidneys collected. Kidney function was evaluated via blood urea nitrogen (BUN) and creatinine (Cr) content; renal histology was examined using transmission electron microscopy (TEM). Kidney levels of phospho-p65 were assessed by Western blot and kidney mRNA levels of interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor (TNF)-α, and p65 by real-time quantitative PCR. Presence of C3 and C5b-9 membrane attack complexes in the kidneys was evaluated via immunohistochemistry. The results showed there was significant swelling, vacuolar degeneration in mitochondria, shrinkage of microvilli, disappearance of brush borders, segmental foot process fusion, and glomerular basement membrane thickening (or disrobing) in kidneys from TCE-sensitized mice. In conjunction with these changes, serum BUN and Cr levels were increased and IL-1β, IL-6, IL-17, and TNFα mRNA levels were elevated. Levels of p65 and phospho-p65 protein were also up-regulated, and there was significant C3 and C5b-9 deposition. PDTC pretreatment attenuated TCE-induced up-regulation of p65 and its phosphorylation, complement deposition, cytokine release, and renal damage. These results provide the first evidence that NF-κB pathway has an important role in TCE-induced renal damage mediated by enhanced complement activation in situ.

Regulatory mechanisms of PD-L1 expression in cancer cells

Immunotherapy targeting the PD-L1/PD-1 pathway using antibodies is effective in the clinical treatment of a multitude of cancers. This makes research of the regulatory mechanisms of PD-1 expression in cancer cells intriguing. PD-L1 expression can be categorized into inducible expression, attributed to extrinsic factors in the microenvironment, and constitutive expression, attributed to intrinsic cancer-driving gene alteration. The mechanisms of PD-L1 expression in cancer cells operate at multiple levels, including gene amplification, chromatin modification, transcription, posttranscription, translation and posttranslation. Moreover, some open questions in this field that need to be answered in future research are proposed. Studies of regulatory mechanisms of PD-L1 expression pave the way for the application of more effective approaches in the future of cancer immunotherapy.

Porphyromonas gingivalis activates NFκB and MAPK pathways in human oral epithelial cells

BACKGROUND

The bacterial biofilm at the gingival margin induces a host immune reaction. In this local inflammation epithelial cells defend the host against bacterial challenge. Porphyromonas gingivalis (P. gingivalis), a keystone pathogen, infects epithelial cells. The aim of this study was to investigate the activation of signaling cascades in primary epithelial cells and oral cancer cell lines by a profiler PCR array.

RESULTS

After infection with P. gingivalis membranes the RNA of 16 to 33 of 84 key genes involved in the antibacterial immune response was up-regulated, amongst them were IKBKB (NF-κB signaling pathway), IRF5 (TLR signaling) and JUN, MAP2K4, MAPK14 and MAPK8 (MAPK pathway) in SCC-25 cells and IKBKB, IRF5, JUN, MAP2K4, MAPK14 and MAPK8 in PHGK. Statistically significant up-regulation of IKBKB (4.7 ×), MAP2K4 (4.6 ×), MAPK14 (4.2 ×) and IRF5 (9.8 ×) (p < 0.01) was demonstrated in SCC-25 cells and IKBKB (3.1 ×), MAP2K4 (4.0 ×) MAPK 14 (3.0 ×) (p < 0.05), IRF5 (3.0 ×) and JUN (7.7 ×) (p < 0.01) were up-regulated in PHGK.

CONCLUSIONS

P. gingivalis membrane up-regulates the expression of genes involved in downstream TLR, NFκB and MAPK signaling pathways involved in the pro-inflammatory immune response in primary and malignant oral epithelial cells.

Induction of B7-H1 receptor by bacterial cells fractions of Porphyromonas gingivalis on human oral epithelial cells: B7-H1 induction by Porphyromonas gingivalis fractions

The immune-regulatory B7-H1 receptor, also known as programmed death-ligand 1 (PD-L1), plays an important role in cell-mediated immune response. It is a co-signaling molecule that mediates regulation of T cell activation and tolerance and is able to negatively regulate activated T cell functions and survival. High expression of B7-H1 in host cells may contribute to the chronicity of inflammatory disorders and represents a possible mechanism of immune evasion. Porphyromonas gingivalis is regarded as a keystone pathogen in periodontitis and is able to invade host cells and disposes a variety of virulence factors including lipopolysaccharide (LPS), fimbriae and proteases such as gingipains. Based on previous studies that demonstrated the capability of P. gingivalis to induce up-regulation of PD-L1 in malignant and non-malignant oral epithelial cells, the aim of the present work was to analyse the potential of various cellular components of P. gingivalis to induce the PD-L1 receptor. Human squamous carcinoma cells and primary gingival keratinocytes were stimulated with total, inner and outer membrane fractions, cytosolic proteins, as well as LPS and peptidoglycans. PD-L1 protein expression was investigated by Western blot analysis and RT-PCR. It was demonstrated that the total membrane fraction induced the highest up-regulation in B7-H1 expression, followed by the outer and inner membrane, whereas cytosolic proteins and LPS did not. In conclusion, we provide evidence that the membrane fraction of P. gingivalis is responsible for up-regulation of the immune-regulatory receptor PD-L1 in squamous carcinoma cells and gingival keratinocytes, and thus may support immune evasion of oral carcinomas.

Oral Squamous Carcinoma Cells Express B7-H1 and B7-DC Receptors in Vivo

B7-H1 and B7-DC ligands are members of the B7 family with important regulatory functions in cell-mediated immune response. Both receptors are ligands of the programmed death receptor PD-1. B7-H1 expression has been detected in the majority of human carcinomas in vivo. B7-H1 mediated signals are able to negatively regulate activated T cell functions and survival, and enable tumor cells to overcome host response. The aim of this study was to investigate the expression of B7-H1 and B7-DC proteins in oral squamous cell carcinomas (OSCC) in vivo. Tissues from 15 samples were cryo-sected and following histological routine staining (HE), incubated with antibodies against human B7-H1 and B7-DC. Immuno-staining of pan-cytokeratin was performed to ascertain the epithelial origin of the tissue and CK 19 to demonstrate the proliferating stage. Confocal laser scanning microscopy confirmed the presence of both B7-H1 and B7-DC in all 15 OSCC. The B7-H1 and B7-DC staining was located in areas of the tissue that were identified as cancerous lesions in the previously stained HE sections before. Staining with Pan-CK and CK19 provided evidence for the epithelial origin and the proliferating stage of the tissue. The in vivo expression of the B7-H1 and B7-DC receptors in oral squamous cell carcinomas suggest that general mechanisms for immune evasion of tumors are also found in OSCC.

IL-12 regulates B7-H1 expression in ovarian cancer-associated macrophages by effects on NF-κB signalling

BACKGROUND AND AIM

B7-H1, a co-inhibitory molecule of the B7 family, is found aberrantly expressed in ovarian cancer cells and infiltrating macrophage/dendritic-like cells, and plays a critical role in immune evasion by ovarian cancer. IL-12, an inducer of Th1 cell development, exerts immunomodulatory effects on ovarian cancer. However, whether IL-12 regulates B7-H1 expression in human ovarian cancer associated-macrophages has not been clarified. Therefore, we investigated the effects of IL-12 on the expression of B7-H1 in ovarian cancer-associated macrophages and possible mechanisms.

METHODS

PMA induced THP-1-derived macrophages or human monocyte-derived macrophages were treated with recombinant IL-12 (rIL-12) or infected with adenovirus carrying human IL-12 gene (Ad-IL-12-GFP) for 24 h, then cocultured with the SKOV3 ovarian cancer cell line for another 24 h. Macrophages were collected for real-time PCR and Western blot to detect the expression of B7-H1, and activation of the NF-κB signaling pathway. Moreover, supernatants were collected to assay for IL-12, IFN-γ and IL-10 by ELISA. In addition, monocyte-derived macrophages treated with IFN-γ were cocultured with SKOV3 and determined for the expression of B7-H1. Furthermore, the expression of B7-H1 in monocyte-derived macrophages was also evaluated after blocking NF-κB signaling.

RESULTS

The expression of B7-H1 was significantly upregulated in monocyte-derived macrophages treated with rIL-12 or Ad-IL-12-GFP compared with the control groups (p<0.05), accompanied by a remarkable upregulation of IFN-γ (p<0.05), a marked downregulation of IL-10 (p<0.05) and activation of NF-κB signaling. However, the upregulation of B7- H1 was inhibited by blocking the NF-κB signaling pathway (p<0.05). Expression of B7-H1 was also increased (p<0.05) in monocyte-derived macrophages treated with IFN-γ and cocultured with SKOV3. By contrast, the expression of B7-H1 in THP-1-derived macrophages was significantly decreased when treated in the same way as monocyte-derived macrophages (p<0.05), and IL-10 was also significantly decreased but IFN-γ was almost absent.

CONCLUSIONS

IL-12 upregulates the expression of B7-H1 in monocyte-derived macrophages, which is possible though inducing the secretion of IFN-γ and further activating the NF-κB signal pathway. However, IL-12 downregulates the expression of B7-H1 in THP-1-derived macrophages, associated with a lack of IFN-γ and inhibition of expression of IL-10.

Both PD-1 ligands protect the kidney from ischemia reperfusion injury

Acute kidney injury (AKI) is a common problem in hospitalized patients that enhances morbidity and mortality and promotes the development of chronic and end-stage renal disease. Ischemia reperfusion injury (IRI) is one of the major causes of AKI and is characterized by uncontrolled renal inflammation and tubular epithelial cell death. Our recent studies demonstrated that regulatory T cells (Tregs) protect the kidney from ischemia reperfusion-induced inflammation and injury. Blockade of programmed death-1 (PD-1) on the surface of Tregs, prior to adoptive transfer, negates their ability to protect against ischemic kidney injury. The present study was designed to investigate the role of the known PD-1 ligands, PD-L1 and PD-L2, in kidney IRI. Administration of PD-L1 or PD-L2 blocking Abs prior to mild or moderate kidney IRI significantly exacerbated the loss of renal function, renal inflammation, and acute tubular necrosis compared with mice receiving isotype control Abs. Interestingly, blockade of both PD-1 ligands resulted in worse injury, dysfunction, and inflammation than did blocking either ligand alone. Genetic deficiency of either PD-1 ligand also exacerbated kidney dysfunction and acute tubular necrosis after subthreshold ischemia. Bone marrow chimeric studies revealed that PD-L1 expressed on non-bone marrow-derived cells is critical for this resistance to IRI. Finally, blockade of either PD-1 ligand negated the protective ability of adoptively transferred Tregs in IRI. These findings suggest that PD-L1 and PD-L2 are nonredundant aspects of the natural protective response to ischemic injury and may be novel therapeutic targets for AKI.

Synergistic effects of IL-4 and TNFα on the induction of B7-H1 in renal cell carcinoma cells inhibiting allogeneic T cell proliferation

Background

The importance of B7-H molecules for the T cell/tumor communication and its impact on renal cell carcinoma (RCC) progression and prognosis has been recently described. Cytokine treatment of RCC has earlier been shown to be beneficial in preclinical settings, but its clinical implementation has not proven to be as effective. This might be partially explained by the yet incomplete picture of cellular alterations in tumor cells upon cytokine treatment investigated in detail in this study.

Methods

RCC tumor cell lines were treated with different cytokines alone or in combination. The constitutive and/or cytokine-induced expression of cytokine receptors signaling components and B7-H molecules in RCC cells were analysed by qPCR and flow cytometry. A mcherry reporter gene construct containing B7-H1 promoter was cloned and its activity was determined upon transfection in cytokine-stimulated cells. Cytokine pretreated tumor cells were co-cultured with allogeneic CD8⁺ T cells from healthy donors and T cell proliferation as well as cytokine secretion was determined.

Results

A heterogeneous, but constitutive B7-H1,-H2,-H3 and H4 expression was found on human RCC cell lines. IL-4 and TNFα treatment led to strong synergistic induction of B7-H1 in RCC cells, whereas B7-H2 was only increased by TNFα. In contrast, B7-H3 and B7-H4 expression were not altered by these cytokines. Treatment of RCC cells with TNFα and IL-4 was accompanied by an activation of signaling molecules like NF-κB, IκB and STAT6. The cytokine-mediated up-regulation of B7-H1 was due to transcriptional control as determined by an increased B7-H1 promoter activity in the presence of IL-4 and TNFα. Despite HLA class I and LFA-1 were also increased, the cytokine-mediated up-regulation of B7-H1 was more pronounced and caused an inhibition of allospecifc CD8⁺ T cell proliferation.

Conclusion

Thus, IL-4 and TNFα, which could be released by immune cells of the tumor microenvironment, are able to control the B7-H1 expression in RCC thereby altering T cell responses. These data are of importance for understanding the complex interplay of tumor cells with immune cells orchestrated by a number of different soluble and membrane bound mediators and for the implementation of check point antibodies directed against B7-H1.

Accelerated tumor growth mediated by sublytic levels of antibody-induced complement activation is associated with activation of the PI3K/AKT survival pathway

PURPOSE

We addressed the possibility that low levels of tumor cell-bound antibodies targeting gangliosides might accelerate tumor growth.

EXPERIMENTAL DESIGN

To test this hypothesis, we treated mice with a range of monoclonal antibody (mAb) doses against GM2, GD2, GD3, and CD20 after challenge with tumors expressing these antigens and tested the activity of the same mAbs in vitro. We also explored the mechanisms behind the complement-mediated tumor growth acceleration that we observed and an approach to overcome it.

RESULTS

Serologically detectable levels of IgM-mAb against GM2 are able to delay or prevent tumor growth of high GM2 expressing cell lines both in vitro and in a SCID mouse model, whereas very low levels of this mAb resulted in slight but consistent acceleration of tumor growth in both settings. Surprisingly, this is not restricted to IgM mAb targeting GM2 but consistent against an IgG mAb targeting GD3 as well. These findings were mirrored by in vitro studies with antibodies against these antigens as well as GD2 and CD20 (with Rituxan), and shown to be complement-dependent in all cases. Complement-mediated accelerated growth of cultured tumor cell lines initiated by low mAb levels was associated with activation of the phosphoinositide 3-kinase (PI3K)/AKT survival pathway and significantly elevated levels of both p-AKT and p-PRAS40. This complement-mediated PI3K activation and accelerated tumor growth in vitro and in vivo are eliminated by PI3K inhibitors NVP-BEZ235 and Wortmannin. These PI3K inhibitors also significantly increased efficacy of high doses of these four mAbs.

CONCLUSION

Our findings suggest that manipulation of the PI3K/AKT pathway and its signaling network can significantly increase the potency of passively administered mAbs and vaccine-induced antibodies targeting a variety of tumor cell surface antigens.

Upregulation of B7-H1 expression is associated with macrophage infiltration in hepatocellular carcinomas

The overexpression of B7-H1 in hepatocellular carcinoma (HCC) mediates HCC immune escape and obstructs the immunotherapy based on tumor-specific CD8+ T cells. Tumor-associated macrophages (TAM) are a major component of cancer-related inflammation and play a central role in tumor promotion. To classify the mechanism underlying the overexpression of B7-H1 in HCC, we examined B7-H1 expression and TAM infiltration in 63 cases of human HCC samples using immunohistochemistry method and found that B7-H1 overexpression was associated with TAM infiltration in HCC tissues. Furthermore, B7-H1 expression was upregulated at both mRNA level and protein level in HCC cells (BEL-7402 and SMMC-7721) cocultured with macrophages in a transwell system. The upregulation of B7-H1 expression induced by macrophage was inhibited by blocking NF-κB or STAT3 signal pathways. These results suggest that overexpression of B7-H1 in HCC may be induced by inflammatory microenvironment involving macrophages and imply that anti-inflammation therapy might be preventive for immune escape and assistant for immunotherapy of HCC.

B7-H1 and B7-DC receptors of oral squamous carcinoma cells are upregulated by Porphyromonas gingivalis

The up-regulation of the B7-H1 receptors in host cells might influence the chronicity of inflammatory disorders that frequently precede the development of human cancers. B7-H1 expression has been detected in the majority of human cancers, leading to anergy and apoptosis of activated T cells, and enabling tumor cells to overcome host response. Porphyromonas gingivalis (P. gingivalis), a putative periodontal pathogen, is an etiologic agent of periodontitis and expresses a variety of virulence factors. In this study, the expression of B7-H1 and B7-DC receptors on squamous cell carcinoma cells SCC-25 and BHY and primary human gingival keratinocytes (PHGK) was analyzed after infection with two virulent P. gingivalis strains in vitro. After 48h, the cells were stained with antibodies for human B7-H1 and B7-DC and further analyzed by flow cytometry. RNA was extracted and gene expression of B7-H1 or B7-DC was quantified by real time PCR. After infection with P. gingivalis, both B7-H1 and B7-DC receptors were up-regulated. The mean fluorescence intensity (MFI) increased from 4.5 to 9.9 (B7-H1) and from 6.9 to 15.0 (B7-DC) (p<0.05, respectively) in SCC-25 cells. PHGK showed an increase from 4.8 to 12.4 (B7-H1) and from 5.5 to 15.6 (B7-DC) (p<0.05, respectively). Streptococcus salivarius K12, a commensal bacterium, caused no up-regulation. After 24h, the expression of B7H1 and B7-DC mRNA in infected cells, normalized to GAPDH and in relation to non-infected cells, was 6.4 fold (B7-H1) and 8.6 fold (B7-DC) higher. In PHGK B7-H1/DC mRNA expression increased 8.2 fold (B7-H1) and 5.9 fold (B7DC) (p<0.05) respectively. The results of the study demonstrate that in contrast to S. salivarius K12 virulent P. gingivalis strains are able to induce the expression of the B7-H1 and B7-DC receptors in squamous carcinoma cells and human gingival keratinocytes, which might facilitate immune evasion by oral cancers.

Sub-lytic C5b-9 induces functional changes in retinal pigment epithelial cells consistent with age-related macular degeneration

PURPOSE

There is evidence for complement dysfunction in age-related macular degeneration (AMD). Complement activation leads to formation of the membrane attack complex (MAC), known to assemble on retinal pigment epithelial (RPE) cells. Therefore, the effect of sub-lytic MAC on RPE cells was examined with regard to pro-inflammatory or pro-angiogenic mediators relevant in AMD.

METHODS

For sub-lytic MAC induction, RPE cells were incubated with an antiserum to complement regulatory protein CD59, followed by normal human serum (NHS) to induce 5% cell death, measured by a viability assay. MAC formation was evaluated by immunofluorescence and FACS analysis. Interleukin (IL)-6, -8, monocytic chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor (VEGF) were quantified by enzyme-linked immunosorbent assay (ELISA). Intracellular MCP-1 was analysed by immunofluorescence, vitronectin by western blotting, and gelatinolytic matrix metalloproteinases (MMPs) by zymography.

RESULTS

Incubation of RPE cells with the CD59 antiserum followed by 5% NHS induced sub-lytic amounts of MAC, verified by FACS and immunofluorescence. This treatment stimulated the cells to release IL-6, -8, MCP-1, and VEGF. MCP-1 staining, production of vitronectin, and gelatinolytic MMPs were also elevated in response to sub-lytic MAC.

CONCLUSIONS

MAC assembly on RPE cells increases the IL-6, -8, and MCP-1 production. Therefore, sub-lytic MAC might have a significant role in generating a pro-inflammatory microenvironment, contributing to the development of AMD. Enhanced vitronectin might be a protective mechanism against MAC deposition. In addition, the increased expression of gelatinolytic MMPs and pro-angiogenic VEGF may be associated with neovascular processes and late AMD.

Stimulation of B7-H1 in hepatocarcinoma cells by hepatitis B virus X antigen

The cross-talk between the hepatitis B virus X protein (HBx) and B7-H1 in hepatocarcinoma (HCC) is unclear. This study analyzed the potential relationships between HBx and B7-H1 in hepatocarcinogenesis. One of human HCC cell lines, HepG2 cells, was transfected to stably express HBx protein (HBx(+)-HepG2). The transcription of B7-H1 mRNA was increased significantly in these cells compared to cells transfected with control vector (HBx(-)-HepG2), as confirmed by a comparative genome-wide microarray analysis (Capitalbio) and real time quantitative PCR (qPCR). Flow cytometry and western-blot further demonstrated that B7-H1 protein synthesis was enhanced in HBx(+)-HepG2 cells. Site-directed mutagenesis of promoter constructs revealed that the transcription factor (NF)-κB binding site between 128 and 137 bp upstream of B7-H1 gene transcriptional start site is primarily responsible for HBx-mediated B7-H1 expression. Co-culture experiments with HBx(+)-HepG2/T cells showed that the number of apoptotic T cells increased profoundly, and this effect could be partially prevented when a neutralizing mAb against B7-H1 was added to the culture, demonstrating that B7-H1 signaling can promote T cell apoptosis. Our results suggest that the expression of B7-H1 in hepatocarcimona cells can be initiated by HBx antigen, thus inducing T cell apoptosis and finally potentially facilitates the genesis of HCC.

Inhibiting the C5-C5a receptor axis

Activation of the complement system is a major pathogenic event that drives various inflammatory responses in numerous diseases. All pathways of complement activation lead to cleavage of the C5 molecule generating the anaphylatoxin C5a and, C5b that subsequently forms the terminal complement complex (C5b-9). C5a exerts a predominant pro-inflammatory activity through interactions with the classical G-protein coupled receptor C5aR (CD88) as well as with the non-G protein coupled receptor C5L2 (GPR77), expressed on various immune and non-immune cells. C5b-9 causes cytolysis through the formation of the membrane attack complex (MAC), and sub-lytic MAC and soluble C5b-9 also possess a multitude of non-cytolytic immune functions. These two complement effectors, C5a and C5b-9, generated from C5 cleavage, are key components of the complement system responsible for propagating and/or initiating pathology in different diseases, including paroxysmal nocturnal hemoglobinuria, rheumatoid arthritis, ischemia-reperfusion injuries and neurodegenerative diseases. Thus, the C5-C5a receptor axis represents an attractive target for drug development. This review provides a comprehensive analysis of different methods of inhibiting the generation of C5a and C5b-9 as well as the signalling cascade of C5a via its receptors. These include the inhibition of C5 cleavage through targeting of C5 convertases or via the C5 molecule itself, as well as blocking the activity of C5a by neutralizing antibodies and pharmacological inhibitors, or by targeting C5a receptors per se. Examples of drugs and naturally occurring compounds used are discussed in relation to disease models and clinical trials. To date, only one such compound has thus far made it to clinical medicine: the anti-C5 antibody eculizumab, for treating paroxysmal nocturnal hemoglobinuria. However, a number of drug candidates are rapidly emerging that are currently in early-phase clinical trials. The C5-C5a axis as a target for drug development is highly promising for the treatment of currently intractable major human diseases.

Interferon-gamma and tumor necrosis factor-alpha induce an immunoinhibitory molecule, B7-H1, via nuclear factor-kappaB activation in blasts in myelodysplastic syndromes

During disease progression in myelodysplastic syndromes (MDS), clonal blasts gain a more aggressive nature, whereas nonclonal immune cells become less efficient via an unknown mechanism. Using MDS cell lines and patient samples, we showed that the expression of an immunoinhibitory molecule, B7-H1 (CD274), was induced by interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) on MDS blasts. This induction was associated with the activation of nuclear factor-kappaB (NF-kappaB) and nearly completely blocked by an NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC). B7-H1(+) MDS blasts had greater intrinsic proliferative capacity than B7-H1(-) MDS blasts when examined in various assays. Furthermore, B7-H1(+) blasts suppressed T-cell proliferation and induced T-cell apoptosis in allogeneic cocultures. When fresh bone marrow samples from patients were examined, blasts from high-risk MDS patients expressed B7-H1 molecules more often compared with those from low-risk MDS patients. Moreover, MDS T cells often overexpressed programmed cell death 1 (PD-1) molecules that transmit an inhibitory signal from B7-H1 molecules. Taken together, these findings provide new insight into MDS pathophysiology. IFNgamma and TNFalpha activate NF-kappaB that in turn induces B7-H1 expression on MDS blasts. B7-H1(+) MDS blasts have an intrinsic proliferative advantage and induce T-cell suppression, which may be associated with disease progression in MDS.