Expression of genes for B7-H3 and other T cell ligands by nasal epithelial cells during differentiation and activation

Bispecific antibody targeting both B7-H3 and PD-L1 exhibits superior antitumor activities

Clinical application of PD-1 and PD-L1 monoclonal antibodies (mAbs) is hindered by their relatively low response rates and the occurrence of drug resistance. Co-expression of B7-H3 with PD-L1 has been found in various solid tumors, and combination therapies that target both PD-1/PD-L1 and B7-H3 pathways may provide  additional therapeutic benefits. Up to today, however, no bispecific antibodies targeting both PD-1 and B7-H3 have reached the clinical development stage. In this study, we generated a stable B7-H3×PD-L1 bispecific antibody (BsAb) in IgG1-VHH format by coupling a humanized IgG1 mAb against PD-L1 with a humanized camelus variable domain of the heavy-chain of heavy-chain antibody (VHH) against human B7-H3. The BsAb exhibited favorable thermostability, efficient T cell activation, IFN-γ production, and antibody-dependent cell-mediated cytotoxicity (ADCC). In a PBMC humanized A375 xenogeneic tumor model, treatment with BsAb (10 mg/kg, i.p., twice a week for 6 weeks) showed enhanced antitumor activities compared to monotherapies and, to some degree, combination therapies. Our results suggest that targeting both PD-1 and B7-H3 with BsAbs increases their specificities to B7-H3 and PD-L1 double-positive tumors and induces a synergetic effect. We conclude that B7-H3×PD-L1 BsAb is favored over mAbs and possibly combination therapies in treating B7-H3 and PD-L1 double-positive tumors.

Spatial proteomics identifies a spectrum of immune dysregulation in acquired bone marrow failure syndromes

Poor graft function (PGF), manifested by multilineage cytopenias and complete donor chimerism post-allogeneic stem cell transplantation (alloSCT), and acquired aplastic anaemia (AA) are immune-mediated acquired bone marrow (BM) failure syndromes with a similar clinical presentation. In this study, we used spatial proteomics to compare the immunobiology of the BM microenvironment and identify common mechanisms of immune dysregulation under these conditions. Archival BM trephines from patients exhibited downregulation of the immunoregulatory protein VISTA and the M2 macrophage marker and suppressor of T-cell activation ARG1 with increased expression of the immune checkpoint B7-H3 compared to normal controls. Increased CD163 and CD14 expression suggested monocyte/macrophage skewing, which, combined with dysregulation of STING and VISTA, is indicative of an environment of reduced immunoregulation resulting in the profound suppression of hematopoiesis in these two conditions. There were no changes in the immune microenvironment between paired diagnostic AA and secondary MDS/AML samples suggesting that leukaemic clones develop in the impaired immune microenvironment of AA without the need for further alterations. Of the eight proteins with dysregulated expression shared by diagnostic AA and PGF, the diagnostic AA samples had a greater fold change in expression than PGF, suggesting that these diseases represent a spectrum of immune dysregulation. Unexpectedly, analysis of samples from patients with good graft function post-alloSCT demonstrated significant changes in the immune microenvironment compared to normal controls, with downregulation of CD44, STING, VISTA, and ARG1, suggesting that recovery of multilineage haematopoiesis post-alloSCT does not reflect recovery of immune function and may prime patients for the development of PGF upon further inflammatory insult. The demonstrable similarities in the immunopathology of AA and PGF will allow the design of clinical interventions that include both patient cohorts to accelerate therapeutic discovery and translation.

Unraveling the Role of Epithelial Cells in the Development of Chronic Rhinosinusitis

The pathophysiology of CRS is multifactorial and complex yet needs to be completed. Recent evidence emphasizes the crucial part played by epithelial cells in the development of CRS. The epithelial cells act as physical barriers and play crucial roles in host defense, including initiating and shaping innate and adaptive immune responses. This review aims to present a comprehensive understanding of the significance of nasal epithelial cells in CRS. New research suggests that epithelial dysfunction plays a role in developing CRS through multiple mechanisms. This refers to issues with a weakened barrier function, disrupted mucociliary clearance, and irregular immune responses. When the epithelial barrier is compromised, it can lead to the passage of pathogens and allergens, triggering inflammation in the body. Furthermore, impaired mucociliary clearance can accumulate pathogens and secretions of inflammatory mediators, promoting chronic inflammation. Epithelial cells can release cytokines and chemokines, which attract and activate immune cells. This can result in an imbalanced immune response that continues to cause inflammation. The interaction between nasal epithelial cells and various immune cells leads to the production of cytokines and chemokines, which can either increase or decrease inflammation. By comprehending the role of epithelial cells in CRS, we can enhance our understanding of the disease's pathogenesis and explore new therapeutics.

Costimulatory and coinhibitory molecules of B7-CD28 family in cardiovascular atherosclerosis: A review

Accumulating evidence supports the active involvement of vascular inflammation in atherosclerosis pathogenesis. Vascular inflammatory events within atherosclerotic plaques are predominated by innate antigen-presenting cells (APCs), including dendritic cells, macrophages, and adaptive immune cells such as T lymphocytes. The interaction between APCs and T cells is essential for the initiation and progression of vascular inflammation during atherosclerosis formation. B7-CD28 family members that provide either costimulatory or coinhibitory signals to T cells are important mediators of the cross-talk between APCs and T cells. The balance of different functional members of the B7-CD28 family shapes T cell responses during inflammation. Recent studies from both mouse and preclinical models have shown that targeting costimulatory molecules on APCs and T cells may be effective in treating vascular inflammatory diseases, especially atherosclerosis. In this review, we summarize recent advances in understanding how APC and T cells are involved in the pathogenesis of atherosclerosis by focusing on B7-CD28 family members and provide insight into the immunotherapeutic potential of targeting B7-CD28 family members in atherosclerosis.

Serum soluble B7-H3 is a prognostic marker for patients with non-muscle-invasive bladder cancer

Background

B7-H3 is a member of the B7 family of immune-regulatory ligands and is a costimulatory molecule promoting the T cell response in vitro. We herein investigated the clinical utility of serum soluble B7-H3 (sB7-H3) in patients with non-muscle invasive bladder cancer (NMIBC).

Methods

We analyzed 555 patients in whom NMIBC was diagnosed at Tokyo Metropolitan Tama Medical Center between 2008 and 2013. We measured the serum sB7-H3 (sB7-H3) level using the enzyme-linked immunosorbent assay (ELISA) and evaluated the utility of sB7-H3 as a prognostic biomarker for NMIBC. We used the Cox proportional hazards regression model to assess recurrence-free survival (RFS) and progression-free survival (PFS) with the sB7-H3 level.

Results

We detected high levels of sB7-H3 in the sera of 47% of patients with NMIBC versus only 8% in healthy donors. The increase of sB7-H3 was significantly associated with poor RFS and PFS. Multivariate analysis showed that elevated sB7-H3 was an independent prognostic factor of RFS and PFS. According to the European Organization for Research and Treatment of Cancer (EORTC), in intermediate-low and intermediate-high risk groups, the presence of sB7-H3 significantly determined the rate of recurrence and progression.

Conclusions

Our data suggested that evaluating serum sB7-H3 expression is a useful tool for predicting the prognosis of patients with NMIBC.

Prognostic values of increased B7 family proteins in haploidentical hematopoietic stem cell transplantation patients with aGVHD

It has been reported that B7H1 and B7H3 play a role in graft-versus-host disease (GVHD), the major cause of treatment-related mortality (TRM) in haploidentical hematopoietic stem cell transplantation (haplo-HSCT) patients; however, the prognostic value of these factors has not been defined. We retrospectively collected 64 haplo-HSCT patients in our hospital from 2013 to 2014, as well as 38 HLA-matched-HSCT patients during the same period as the control group. We analyzed B7H1, B7H3, PD1, soluble CD25, ST2 and TNFR1 at 0 day, + 7 days, + 14 days and + 28 days after HSCT. The + 7 days/+ 14 days B7H1/B7H3 and + 28 days ST2 serum levels were higher in patients with aGVHD who underwent haplo-HSCT. Moreover, + 7 days B7H1/B7H3 serum levels were predictive of grade III-IV aGVHD (B7H1: AUC = 0.830, P < 0.001; B7H3: AUC = 0.775, P = 0.001). Haplo-HSCT patients with higher + 7 days B7H1/B7H3 or + 28 days ST2 serum levels had poor GVHD-related mortality (GRM) (B7H1: P < 0.001; B7H3: P = 0.002; ST2: P = 0.047). Multivariate analysis revealed that the + 7 days B7H1 serum level (P = 0.041), as well as viral infection (P = 0.015) and donor age (P = 0.012), could independently predict GRM. Collectively, we found that + 7 days B7H1/B7H3 serum levels can predict grade III-IV aGVHD, while only the + 7 days B7H1 serum level, together with viral infection and donor age, could independently predict GRM in patients with haplo-HSCT.

B7-H3 expression in donor T cells and host cells negatively regulates acute graft-versus-host disease lethality

Members of the B7 family have been shown to be important for regulating immune responses by providing either positive or negative costimulatory signals. The function of B7-H3 has been controversial. We show that B7-H3 is upregulated in graft-versus-host disease (GVHD) target organs, including the colon, liver, and lung. Infusion of allogeneic donor T cells into B7-H3(-/-) vs wild-type (WT) recipients resulted in increased GVHD lethality associated with increased T-cell proliferation, colonic inflammatory cytokines, and destruction of epithelial barriers. Allogeneic B7-H3(-/-) vs WT donor T cells also had increased T-cell proliferation and GVHD lethality associated with increased proliferation and cytokine secretion in the spleen, intraepithelial lymphocyte inflammatory cytokines, and intestinal permeability. Both resting and activated regulatory T cells (Tregs) lack B7-H3 messenger RNA. Consistent with these data, GVHD was augmented in recipients of B7-H3(-/-) Treg-depleted grafts. In two delayed lymphocyte infusion (DLI) models, T cells lacking B7-H3 are capable of providing graft-versus-leukemia (GVL) effects. We conclude that B7-H3 is responsible for providing a negative costimulatory signal. Our studies provide support for developing and testing new therapies directed toward the B7-H3 pathway, including approaches to augment host B7-H3 early after bone marrow transplantation to prevent GVHD and to develop potent antagonistic antibodies later after transplant to facilitate DLI-mediated GVL without GVHD complications.

Clinical significance of the induction of macrophage differentiation by the costimulatory molecule B7-H3 in human non-small cell lung cancer

B7-H3, a member of the B7 family of molecules, is expressed in certain types of human cancer and is important in tumor development and progression. Although several studies have reported that the expression of B7-H3 is correlated with poor outcomes in patients with cancer, its exact role in cancer remains unknown. In the present study, the expression levels of B7-H3 in the pathological specimens of 105 patients treated for non-small cell lung cancer (NSCLC) were examined by immunohistochemistry. A high expression level of B7-H3 was observed in 46.9% of the 105 NSCLC tissue specimens. These patients demonstrated a more advanced tumor grade and a shorter survival time. In addition, we also examined the levels of tumor-associated macrophages (TAMs) in NSCLC tissues and observed that the levels were positively correlated with the expression of B7-H3, and that higher levels of macrophages were associated with lower levels of infiltrating T cells and a shorter survival time. These results demonstrated that TAMs are important in the evasion of tumor immune surveillance in NSCLC. Furthermore, through knockdown of B7-H3 by RNA interference, we observed that soluble B7-H3 was capable of inducing macrophages to express higher levels of macrophage mannose receptor (MMR) and lower levels of human leukocyte antigen (HLA)-DR, as well as higher levels of interleukin-10 (IL-10) and lower levels of IL-1β in vitro. These observations are characteristic of an anti-inflammatory/reparatory (alternative/M2) phenotype. Therefore, our data suggests that B7-H3 proteins are involved in the progression of NSCLC by inducing the development of monocytes into anti-inflammatory cells.

Functional analysis of B7-H3 in colonic carcinoma cells

B7-H3 is a newly discovered member of the B7/CD28 superfamily which functions as an important T-cell immune molecule. It has been reported recently that B7-H3 is highly expressed in many cancer cells, the data indicating that it may be a regulation factor contributing to tumor-resistance. In our study, we used bioinformatics to identify differentially expressed genes between colonic cancer cells and normal colonic cells, aiming to analyze mechanisms and identify sub-pathways closely related to progression, with the final aim of finding small molecule drugs which might interfere this progression. We found that ajmaline is one related factor which may enhance self-immunity in colon carcinoma therapy and B7-H3 plays important roles with regard to immunoreactions of colonic cancer cells. All the results indicate that H7-B3 is a favorable prognostic biomarker for colon carcinomas, providing novel information regarding likely targets for intervention.

Enhancement of effector CD8+ T-cell function by tumour-associated B7-H3 and modulation of its counter-receptor triggering receptor expressed on myeloid cell-like transcript 2 at tumour sites

SUMMARY

B7-H3 is a B7-family co-stimulatory molecule and is broadly expressed on various tissues and immune cells. Transduction of B7-H3 into some tumours enhances anti-tumour responses. We have recently found that a triggering receptor expressed on myeloid cell-like transcript 2 (TLT-2) is a receptor for B7-H3. Here, we examined the roles of tumour-associated B7-H3 and the involvement of TLT-2 in anti-tumour immunity. Ovalbumin (OVA)(257-264)-specific OT-I CD8(+) T cells exhibited higher cytotoxicity against B7-H3-transduced OVA-expressing tumour cells (B7-H3/E.G7) in vitro and selectively eliminated B7-H3/E.G7 cells in vivo. The presence of B7-H3 on target cells efficiently augmented CD8(+) T-cell-mediated cytotoxicity against alloantigen or OVA, whereas the presence of B7-H3 in the priming phase did not affect the induced cytotoxicity. B7-H3 transduction into five tumour cell lines efficiently reduced their tumorigenicity and regressed growth. Treatment with either anti-B7-H3 or anti-TLT-2 monoclonal antibody accelerated growth of a tumour that expressed endogenous B7-H3, suggesting a co-stimulatory role of the B7-H3-TLT-2 pathway. The TLT-2 was preferentially expressed on CD8(+) T cells in regional lymph nodes, but was down-regulated in tumour-infiltrating CD8(+) T cells. Transduction of TLT-2 into OT-I CD8(+) T cells enhanced antigen-specific cytotoxicity against both parental and B7-H3-transduced tumour cells. Our results suggest that tumour-associated B7-H3 directly augments CD8(+) T-cell effector function, possibly by ligation of TLT-2 on tumour-infiltrating CD8(+) T cells at the local tumour site.

Expression and function of the inducible costimulator ligand B7-H2 in human airway smooth muscle cells

BACKGROUND

B7-H2 is a ligand for the inducible costimulator (ICOS). The aim of this study was to examine the expression and function of B7-H2 in human airway smooth muscle (ASM) cells and compare them with those of CD40 or OX40 ligand (OX40L).

METHODS

Expression of B7-H2, CD40 and OX40L in ASM cells and their respective counterparts in T cells was analyzed by RT-PCR or flow cytometry. The modulating effect of polyinosinic-polycytidylic acid (poly I:C) on expression of B7-H2, CD40 and OX40L was also examined. The function of these three molecules was evaluated by virtue of adhesion of anti-CD3-activated T cells, IL-6 and IL-8 production and DNA synthesis.

RESULTS

ASM cells constitutively expressed B7-H2, CD40 and OX40L that mediated adhesion of activated T cells expressing ICOS, CD40L and OX40. ASM cells responded to poly I:C with upregulated expression of B7-H2, CD40 and OX40L and displayed enhanced adhesion of activated T cells. Functional analysis performed on untreated ASM cells showed that engagement of B7-H2 with ICOS-Ig clearly induced DNA synthesis, whereas that of CD40 or OX40L with trimeric CD40L or OX40-Ig greatly increased IL-6 and IL-8 production. These responses were enhanced in poly I:C-treated ASM cells.

CONCLUSIONS

The data demonstrate that ASM cells express functionally active B7-H2, CD40 and OX40L and suggest that B7-H2-dependent signaling may play an active role in a proliferative response rather than in cytokine and chemokine production. In addition, the modulation of B7-H2, CD40 and OX40L expression and function by poly I:C may have important implications for the function of virus-infected ASM cells.

Technical advances in rhinologic basic science research

Chronic rhinosinusitis (CRS) is the single most common self-reported chronic health condition in the United States and is estimated to affect 16% of the adult population annually. Despite the prevalence of this disease, there still exists an incomplete understanding of CRS pathophysiology. In this review, the authors highlight technological advances in rhinology: real-time polymerase chain reaction, epithelial cell culture, flow cytometry, genomics/single-nucleotide polymorphism detection, microarrays, and genetic/nongenetic animal models of sinusitis. The purpose of this review is to describe these methodologies and their contributions toward achieving a better understanding of CRS.

Fine tuning the immune response through B7-H3 and B7-H4

SUMMARY

B7-H3 and B7-H4 belong to a new class of immune regulatory molecules, which primarily execute their functions in peripheral tissues to fine tune immune responses in target organs. In normal circumstances, while the mRNA for both molecules is broadly distributed, tight control at the post-transcriptional level is imposed. Under a pathogenic environment, such as inflammation and cancer, the control is often aberrant. Upon engaging their receptors, these molecules regulate the immune response in positive or negative ways depending on the expression and type of cells bearing the receptors. Thus, manipulation of the expression of these molecules and/or their receptors may represent a realistic opportunity to fine tune immune responses and to design new immunotherapeutic approaches.

Modulation of Immune Response by B7 Family Molecules in Tumor Microenvironments

The importance of co-stimulatory and co-inhibitory molecules has been confirmed on a grand scale; with the identification of new B7 family molecules, possessing both immune activating and inhibiting functions, this family has exploded onto the scene of immune regulation. Nowhere, however, has the role of B7 family members been more apparent than in the fight against cancer. In this review, we will discuss recent data regarding the essential and complex role of B7 family members in regulating the immune response within tumor microenvironment.

Chitin stimulates expression of acidic mammalian chitinase and eotaxin-3 by human sinonasal epithelial cells in vitro

BACKGROUND

Sinonasal epithelial cells participate in host defense by initiating innate immune mechanisms against potential pathogens. Antimicrobial innate mechanisms have been shown to involve Th1-like inflammatory responses. Although epithelial cells can also be induced by Th2 cytokines to express proeosinophilic mediators, no environmental agents have been identified that promote this effect.

METHODS

Human sinonasal epithelial cells from patients with chronic rhinosinusitis with nasal polyps (CRSwNPs) and controls were harvested and grown in primary culture. Cell cultures were exposed to a range of concentrations of chitin for 24 hours, and mRNA for acidic mammalian chitinase (AMCase), eotaxin-3, and thymic stromal-derived lymphopoietin (TSLP) were assessed. Other cultures were exposed to interleukin 4 (IL- 4) alone and in combination with dust-mite antigen (DMA) for 36 hours. Extracted mRNA and cell culture supernatant were analyzed for expression of AMCase and eotaxin-3.

RESULTS

Chitin induced a dose-dependent expression of AMCase and eotaxin-3 mRNA but not TSLP. Patients with recalcitrant CRSwNPs showed lower baseline expression of AMCase when compared with treatment-responsive CRSwNP and less induction of AMCase expression by chitin. DMA did not directly induce expression of AMCase or eotaxin-3. Expression of eotaxin-3 was stimulated by IL-4 and further enhanced with the addition of DMA. Levels of AMCase were not significantly affected by either IL-4 or DMA exposure. In some cases, the combination of IL-4 and DMA was able to induce AMCase expression in cell cultures not producing AMCase at baseline.

CONCLUSION

The abundant biopolymer chitin appears to be recognized by a yet uncharacterized receptor on sinonasal epithelial cells. Chitin stimulates production of AMCase and eotaxin-3, two pro-Th2 effector proteins. This finding suggests the existence of a novel innate immune pathway for local defense against chitin-containing organisms in the sinonasal tract. Dysregulation of this function could precipitate or exacerbate Th2 inflammation, potentially acting as an underlying factor in recalcitrant CRSwNP.

Triggering receptor expressed on myeloid cell-like transcript 2 (TLT-2) is a counter-receptor for B7-H3 and enhances T cell responses

The B7 family member B7-H3 (CD276) plays important roles in immune responses. However, the function of B7-H3 remains controversial. We found that murine B7-H3 specifically bound to Triggering receptor expressed on myeloid cells (TREM)-like transcript 2 (TLT-2, TREML2). TLT-2 was expressed on CD8(+) T cells constitutively and on activated CD4(+) T cells. Stimulation with B7-H3 transfectants preferentially up-regulated the proliferation and IFN-gamma production of CD8(+) T cells. Transduction of TLT-2 into T cells resulted in enhanced IL-2 and IFN-gamma production via interactions with B7-H3. Blockade of the B7-H3:TLT-2 pathway with a mAb against B7-H3 or TLT-2 efficiently inhibited contact hypersensitivity responses. Our results demonstrate a direct interaction between B7-H3 and TLT-2 that preferentially enhances CD8(+) T cell activation.

Regulation of COX-2 expression and IL-6 release by particulate matter in airway epithelial cells

Particulate matter (PM) in ambient air is a risk factor for human respiratory and cardiovascular diseases. The delivery of PM to airway epithelial cells has been linked to release of proinflammatory cytokines; however, the mechanisms of PM-induced inflammatory responses are not well-characterized. This study demonstrates that PM induces cyclooxygenase (COX)-2 expression and IL-6 release through both a reactive oxygen species (ROS)-dependent NF-kappaB pathway and an ROS-independent C/EBPbeta pathway in human bronchial epithelial cells (HBEpCs) in culture. Treatment of HBEpCs with Baltimore PM induced ROS production, COX-2 expression, and IL-6 release. Pretreatment with N-acetylcysteine (NAC) or EUK-134, in a dose-dependent manner, attenuated PM-induced ROS production, COX-2 expression, and IL-6 release. The PM-induced ROS was significantly of mitochondrial origin, as evidenced by increased oxidation of the mitochondrially targeted hydroethidine to hydroxyethidium by reaction with superoxide. Exposure of HBEpCs to PM stimulated phosphorylation of NF-kappaB and C/EBPbeta, while the NF-kappaB inhibitor, Bay11-7082, or C/EBPbeta siRNA attenuated PM-induced COX-2 expression and IL-6 release. Furthermore, NAC or EUK-134 attenuated PM-induced activation of NF-kappaB; however, NAC or EUK-134 had no effect on phosphorylation of C/EBPbeta. In addition, inhibition of COX-2 partly attenuated PM-induced Prostaglandin E2 and IL-6 release.

The cigarette smoke component acrolein inhibits expression of the innate immune components IL-8 and human beta-defensin 2 by sinonasal epithelial cells

BACKGROUND

Tobacco use is associated with poorer outcomes of medical and surgical therapy for chronic rhinosinusitis (CRS), although the underlying mechanism is unknown. Acrolein (AC) is a major component of cigarette smoke that has been shown to suppress innate immune gene expression by human bronchial epithelial cells and murine macrophages. In this study, we explore whether exposure of human sinonasal epithelial cells (HSNECs) to AC similarly reduces their innate immune gene expression.

METHODS

Primary HSNECs from CRS patients were grown in culture, either differentiated or submerged. HSNECs were treated for 30 minutes with 0-50 microM of AC and were subsequently analyzed by real-time polymerase chain reaction and ELISA to determine IL-8 and human beta-defensin (HBD) 2 expression. Total glutathione was measured to see the oxidative stress within the treatment range.

RESULTS

In primary HSNEC, IL-8 mRNA levels decreased dose dependently in the range of 10-50 microM of AC with an eightfold decrease at 50 microM. In addition, a 125-fold decrease at 50 microM for IL-8 protein was observed. HBD-2 mRNA decreased twofold and HBD-2 protein decreased fourfold at 50 microM of AC in primary HSNEC. However, differentiated HSNEC showed a marginal decrease in a dose-dependent manner for both IL-8 and HBD-2 within the range of 10-50 microM of AC. There was no oxidative stress observed over this range of AC concentration.

CONCLUSION

The tobacco smoke component AC has the capacity to suppress the inflammatory and innate immune function of sinonasal epithelial cells. Whether this effect contributes to the negative clinical impact of smoking on CRS outcomes merits additional investigation.

The new B7s: playing a pivotal role in tumor immunity

B7-H1, B7-DC, B7-H2, B7-H3, and B7-H4, all new additions to the B7 family, here termed "the new B7s," are emerging as important tools in directing immune function; each with unique, yet often overlapping functions. Clearly, each B7 molecule has developed its own indispensable niche in the immune system. The expression of both stimulatory and inhibitory B7 molecules seems to play an essential role in regulating the immune response to transformed cells through a variety of mechanisms. As specific niches of B7 family members continue to be dissected, their diagnostic and therapeutic potential becomes ever more apparent. In this review, we will discuss the role of the new B7s in activation and inhibition of antitumor immune responses, their prospects in diagnostics, and also potential and developing immunotherapy protocols.

Sinonasal epithelial cell expression of toll-like receptor 9 is decreased in chronic rhinosinusitis with polyps

BACKGROUND

Innate immune recognition of pathogens by sinonasal epithelial cells may play an important role in the pathogenesis of chronic rhinosinusitis (CRS). Previous studies have indicated that toll-like receptor (TLR) mRNA is present in sinonasal mucosa, and levels of TLR9 expression are decreased in recalcitrant CRS with nasal polyps (CRSwNP). However, the cellular source and function of TLR9 in the sinonasal epithelium is not known. In this study, primary epithelial cell cultures were analyzed from control subjects and CRSwNP patients to determine the presence and function of TLR9 protein.

METHODS

Primary epithelial cell cultures were established from 5 controls and 10 CRSwNP patients undergoing sinus surgery. Flow cytometry was used to confirm purity of epithelial cells and to assess expression of TLR9 protein. Epithelial cells were stimulated with TLR9 agonist, and mRNA was analyzed by real-time PCR for expression of human beta-defensin (HBD) 2 and interleukin (IL)-8.

RESULTS

Flow cytometry showed TLR9 protein in 100% of epithelial cells from controls and CRSwNP patients. The level of expression was 50% lower in CRS patients than in controls. Stimulation of epithelial cells with TLR9 agonist produced a 1.5- to 9-fold increase in HBD-2 and IL-8 mRNA expression.

CONCLUSION

Functional TLR9 protein is expressed by normal and diseased sinonasal epithelial cells. The level of TLR9 expression is decreased in CRSwNP patients, consistent with the previous finding of decreased TLR9 mRNA in whole sinonasal tissue. These findings suggest that impaired innate immune responses to pathogens via TLR9 on sinonasal epithelial cells may represent a critical mechanism in chronic inflammatory sinus disease.

Integrin signalling regulates the nuclear localization and function of the lysophosphatidic acid receptor-1 (LPA1) in mammalian cells

We show that LPA1 (lysophosphatidic acid receptor-1) is constitutively localized in the nucleus of mammalian cells. LPA1 also traffics from cell membranes to the nucleus in response to LPA (lysophosphatidic acid). Several lines of evidence suggest an important role for cell-matrix interaction in regulating the constitutive nuclear localization of LPA1. First, the RGDS peptide, which blocks cell matrix-induced integrin clustering and cytoskeletal rearrangement, reduced the number of cells containing LPA1 in the nucleus. Secondly, a higher proportion of cells contained nuclear LPA1 when adhesion on fibronectin-coated glass was compared with adherence to polylysine-coated glass. Thirdly, pre-treatment of cells with the Rho kinase inhibitor (Y27632) or the myosin light chain kinase inhibitor (ML9) reduced the number of cells containing nuclear LPA1. The addition of LPA and/or Ki16425 (which binds to LPA1) to isolated nuclei containing LPA1 induced the phosphorylation of several proteins with molecular masses of 34, 32, 14 and 11 kDa. These findings demonstrate that trafficking of LPA1 to the nucleus is influenced by cell-matrix interactions and that nuclear LPA1 may be involved in regulating intranuclear protein phosphorylation and signalling.

Regulation of lysophosphatidic acid-induced epidermal growth factor receptor transactivation and interleukin-8 secretion in human bronchial epithelial cells by protein kinase Cdelta, Lyn kinase, and matrix metalloproteinases

We have demonstrated earlier that lysophosphatidic acid (LPA)-induced interleukin-8 (IL-8) secretion is regulated by protein kinase Cdelta (PKCdelta)-dependent NF-kappaB activation in human bronchial epithelial cells (HBEpCs). Here we provide evidence for signaling pathways that regulate LPA-mediated transactivation of epidermal growth factor receptor (EGFR) and the role of cross-talk between G-protein-coupled receptors and receptor-tyrosine kinases in IL-8 secretion in HBEpCs. Treatment of HBEpCs with LPA stimulated tyrosine phosphorylation of EGFR, which was attenuated by matrix metalloproteinase (MMP) inhibitor (GM6001), heparin binding (HB)-EGF inhibitor (CRM 197), and HB-EGF neutralizing antibody. Overexpression of dominant negative PKCdelta or pretreatment with a PKCdelta inhibitor (rottlerin) or Src kinase family inhibitor (PP2) partially blocked LPA-induced MMP activation, proHB-EGF shedding, and EGFR tyrosine phosphorylation. Down-regulation of Lyn kinase, but not Src kinase, by specific small interfering RNA mitigated LPA-induced MMP activation, proHB-EGF shedding, and EGFR phosphorylation. In addition, overexpression of dominant negative PKCdelta blocked LPA-induced phosphorylation and translocation of Lyn kinase to the plasma membrane. Furthermore, down-regulation of EGFR by EGFR small interfering RNA or pretreatment of cells with EGFR inhibitors AG1478 and PD158780 almost completely blocked LPA-dependent EGFR phosphorylation and partially attenuated IL-8 secretion, respectively. These results demonstrate that LPA-induced IL-8 secretion is partly dependent on EGFR transactivation regulated by PKCdelta-dependent activation of Lyn kinase and MMPs and proHB-EGF shedding, suggesting a novel mechanism of cross-talk and interaction between G-protein-coupled receptors and receptor-tyrosine kinases in HBEpCs.

Differential regulation of hyaluronan-induced IL-8 and IP-10 in airway epithelial cells

Airway epithelium is emerging as a regulator of local inflammation and immune responses. However, the cellular and molecular mechanisms responsible for the immune modulation by these cells have yet to be fully elucidated. At the cellular level, the hallmarks of airway inflammation are mucus gland hypertrophy with excess mucus production, accumulation of inflammatory mediators, inflammation in the airway walls and lumen, and breakdown and turnover of the extracellular matrix. We demonstrate that fragments of the extracellular matrix component hyaluronan induce inflammatory chemokine production in primary airway epithelial cells grown at an air-liquid interface. Furthermore, hyaluronan fragments use two distinct molecular pathways to induce IL-8 and IFN-gamma-inducible protein 10 (IP-10) chemokine expression in airway epithelial cells. Hyaluronan-induced IL-8 requires the MAP kinase pathway, whereas hyaluronan-induced IP-10 utilizes the NF-kappaB pathway. The induction is specific to low-molecular-weight hyaluronan fragments as other glycosaminoglycans do not induce IL-8 and IP-10 in airway epithelial cells. We hypothesize that not only is the extracellular matrix a target of destruction in airway inflammation but it plays a critical role in perpetuating inflammation through the induction of cytokines, chemokines, and modulatory enzymes in epithelial cells. Furthermore, hyaluronan, by inducing IL-8 and IP-10 by distinct pathways, provides a unique target for differential regulation of key inflammatory chemokines.

Transcriptional regulation of lysophosphatidic acid-induced interleukin-8 expression and secretion by p38 MAPK and JNK in human bronchial epithelial cells

HBEpCs (human bronchial epithelial cells) contribute to airway inflammation by secreting a variety of cytokines and chemokines in response to allergens, pathogens, viruses and environmental toxins and pollutants. The potent neutrophil chemoattractant, IL-8 (interleukin-8), is a major cytokine secreted by HBEpCs. We have recently demonstrated that LPA (lysophosphatidic acid) stimulated IL-8 production in HBEpCs via protein kinase C delta dependent signal transduction. However, mechanisms of IL-8 expression and secretion are complex and involve multiple protein kinases and transcriptional factors. The present study was undertaken to investigate MAPK (mitogen-activated protein kinase) signalling in the transcriptional regulation of IL-8 expression and secretion in HBEpCs. Exposure of HBEpCs to LPA (1 microM) enhanced expression and secretion of IL-8 by 5-8-fold and stimulated threonine/tyrosine phosphorylation of ERK (extracellular-signal-regulated kinase), p38 MAPK and JNK (c-Jun N-terminal kinase). The LPA-induced secretion of IL-8 was blocked by the p38 MAPK inhibitor SB203580, by p38 MAPK siRNA (small interfering RNA), and by the JNK inhibitor JNK(i) II, but not by the MEK (MAPK/ERK kinase) inhibitor, PD98059. LPA enhanced the transcriptional activity of the IL-8 gene; that effect relied on activation of the transcriptional factors NF-kappaB (nuclear factor kappaB) and AP-1 (activator protein-1). Furthermore, SB203580 attenuated LPA-dependent phosphorylation of IkappaB (inhibitory kappaB), NF-kappaB and phospho-p38 translocation to the nucleus, NF-kappaB transcription and IL-8 promoter-mediated luciferase reporter activity, without affecting the JNK pathway and AP-1 transcription. Similarly, JNK(i) II only blocked LPA-mediated phosphorylation of JNK and c-Jun, AP-1 transcription and IL-8 promoter-mediated luciferase reporter activity, without blocking p38 MAPK-dependent NF-kappaB transcription. Additionally, siRNA for LPA(1-3) receptors partially blocked LPA-induced IL-8 production and activation of MAPKs. The LPA1 and LPA3 receptors, as compared with LPA2, were most efficient in transducing LPA-mediated IL-8 production. These results show an independent role for p38 MAPK and JNK in LPA-induced IL-8 expression and secretion via NF-kappaB and AP-1 transcription respectively in HBEpCs.

Transcriptional regulation of lysophosphatidic acid-induced interleukin-8 expression and secretion by p38 MAPK and JNK in human bronchial epithelial cells

HBEpCs (human bronchial epithelial cells) contribute to airway inflammation by secreting a variety of cytokines and chemokines in response to allergens, pathogens, viruses and environmental toxins and pollutants. The potent neutrophil chemoattractant, IL-8 (interleukin-8), is a major cytokine secreted by HBEpCs. We have recently demonstrated that LPA (lysophosphatidic acid) stimulated IL-8 production in HBEpCs via protein kinase C delta dependent signal transduction. However, mechanisms of IL-8 expression and secretion are complex and involve multiple protein kinases and transcriptional factors. The present study was undertaken to investigate MAPK (mitogen-activated protein kinase) signalling in the transcriptional regulation of IL-8 expression and secretion in HBEpCs. Exposure of HBEpCs to LPA (1 microM) enhanced expression and secretion of IL-8 by 5-8-fold and stimulated threonine/tyrosine phosphorylation of ERK (extracellular-signal-regulated kinase), p38 MAPK and JNK (c-Jun N-terminal kinase). The LPA-induced secretion of IL-8 was blocked by the p38 MAPK inhibitor SB203580, by p38 MAPK siRNA (small interfering RNA), and by the JNK inhibitor JNK(i) II, but not by the MEK (MAPK/ERK kinase) inhibitor, PD98059. LPA enhanced the transcriptional activity of the IL-8 gene; that effect relied on activation of the transcriptional factors NF-kappaB (nuclear factor kappaB) and AP-1 (activator protein-1). Furthermore, SB203580 attenuated LPA-dependent phosphorylation of IkappaB (inhibitory kappaB), NF-kappaB and phospho-p38 translocation to the nucleus, NF-kappaB transcription and IL-8 promoter-mediated luciferase reporter activity, without affecting the JNK pathway and AP-1 transcription. Similarly, JNK(i) II only blocked LPA-mediated phosphorylation of JNK and c-Jun, AP-1 transcription and IL-8 promoter-mediated luciferase reporter activity, without blocking p38 MAPK-dependent NF-kappaB transcription. Additionally, siRNA for LPA(1-3) receptors partially blocked LPA-induced IL-8 production and activation of MAPKs. The LPA1 and LPA3 receptors, as compared with LPA2, were most efficient in transducing LPA-mediated IL-8 production. These results show an independent role for p38 MAPK and JNK in LPA-induced IL-8 expression and secretion via NF-kappaB and AP-1 transcription respectively in HBEpCs.

The B7 family revisited

The discovery of new functions for the original B7 family members, together with the identification of additional B7 and CD28 family members, have revealed new ways in which the B7:CD28 family regulates T cell activation and tolerance. B7-1/B7-2:CD28 interactions not only promote initial T cell activation but also regulate self-tolerance by supporting CD4+CD25+ T regulatory cell homeostasis. CTLA-4 can exert its inhibitory effects in both B7-1/B7-2 dependent and independent fashions. B7-1 and B7-2 can signal bidirectionally by engaging CD28 and CTLA-4 on T cells and by delivering signals into B7-expressing cells. The five new B7 family members, ICOS ligand, PD-L1 (B7-H1), PD-L2 (B7-DC), B7-H3, and B7-H4 (B7x/B7-S1) are expressed on professional antigen-presenting cells as well as on cells within nonlymphoid organs, providing new means for regulating T cell activation and tolerance in peripheral tissues. The new CD28 families members, ICOS, PD-1, and BTLA, are inducibly expressed on T cells, and they have important roles in regulating previously activated T cells. PD-1 and BTLA also are expressed on B cells and may have broader immunoregulatory functions. The ICOS:ICOSL pathway appears to be particularly important for stimulating effector T cell responses and T cell-dependent B cell responses, but it also has an important role in regulating T cell tolerance. In addition, the PD-1:PD-L1/PD-L2 pathway plays a critical role in regulating T cell activation and tolerance. In this review, we revisit the roles of the B7:CD28 family members in regulating immune responses, and we discuss their therapeutic potential.